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The last post dealt with the link between highly processed food and increased risk of cancer. Now an interesting article written by Dr. Lisa Mosconi (Associate Director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College/New York -Presbyterian Hospital) refers to that study when discussing research about lifestyles (and especially diet) and later Alzheimer's disease.

It'll be interesting to see how this research plays out - is her approach stressing diet (and avoiding ultra-processed food and trans fats) and lifestyle correct or not? Much of what she says definitely makes sense and is supported by research, such as the negative health effects of chronic inflammation, and how eating actual, real foods has beneficial health effects. On the other hand, vitamin, mineral, and fish oil supplements generally don't show those health benefits (as she discusses here).

Currently there are a number of theories about causes of Alzheimer's disease (including the role of microbes), as well as a number of drug treatments that so far have gone nowhere. If Dr. Mosconi's research interests you, then read the interview she did in 2017. [In the interview she talks about the importance of exercise, intellectual stimulation, social networks, and the benefits of eating real foods rather than supplements. She recommends: drink water, eat fish, eat vegetables and fruit, eat glucose rich foods, and don't eat highly processed and fast foods.]  From Quartz:

The road to Alzheimer’s disease is lined with processed foods

Dementia haunts the United States. There’s no one without a personal story about how dementia has touched someone they care for. But beyond personal stories, the broader narrative is staggering: By 2050, we are on track to have almost 15 million Alzheimer’s patients in the US alone. ... It’s an epidemic that’s already underway—but we don’t recognize it as such. The popular conception of Alzheimer’s is as an inevitable outcome of aging, bad genes, or both.  ...continue reading "Ultra-Processed Foods and Alzheimer’s?"

A new observational study from Taiwan found that having one of eight chronic diseases, such as heart disease or diabetes, or their markers (e.g. high cholesterol levels as a marker for heart disease), also significantly raises the person's odds of developing cancer or dying from cancer. The study estimated that these diseases or markers accounted for about 20% of all new cancers and 39% of all cancer deaths. That's about the risk of 5 lifestyle factors combined (smoking, alcohol consumption, obesity, unhealthy diet, and lack of exercise) contributing to cancer development and death.

The eight chronic diseases and markers were: cardiovascular disease (markers for which include blood pressure, total cholesterol, and heart rate), diabetes, chronic kidney disease (markers for which include proteinuria and glomerular filtration rate), pulmonary disease, and gouty arthritis (for which uric acid is a marker). The higher the chronic disease and marker score, the higher the risk of developing cancer and cancer death (a dose-response). Chronic diseases and markers were associated with a shortened lifespan -  about 13.3 years in men and 15.9 years in women.

But the good news is that regular physical exercise lowers the risk of developing cancer by about 48% and the risk of cancer death by 27%. That's huge!  So physical exercise and activity could be viewed as "cancer prevention" strategies. The researchers pointed out that additional cancer prevention strategies are avoiding smoking (very important), avoiding excessive alcohol consumption, maintaining healthy weight, and a healthy diet. From Science Daily:

Substantial impact of chronic diseases on cancer risk

Several common chronic diseases together account for more than a fifth of new cancer cases and more than a third of cancer deaths, finds a study published by The BMJ today. The findings show that the cancer risks from common chronic diseases, such as heart disease and diabetes, are as important as those from five major lifestyle factors combined.

A team of researchers based in the US and Taiwan therefore set out to investigate the combined effect of eight common chronic diseases or disease markers (for example, high blood pressure as a marker of heart disease) on cancer risk compared with lifestyle factorsThey also explored whether physical activity could reduce the cancer risk associated with chronic diseases and disease markers. The study involved 405,878 men and women in Taiwan with no history of cancer .... underwent a series of medical tests between 1996 and 2007. .... Participants were followed for an average of 8.7 years.

The researchers found that cardiovascular disease markers, diabetes, chronic kidney disease markers, pulmonary disease, and gouty arthritis marker were individually associated with risk of developing cancer or cancer death. Higher chronic disease risk scores based on these diseases or markers were linked with an increased risk of developing cancer and cancer death, with the highest level associated with a more than twofold increase in risk of developing cancer and a fourfold increase in risk of cancer death.

High chronic disease risk scores were also associated with substantial reduction in life span. The highest scores were associated with 13.3 years of life lost in men and 15.9 years of life lost in women. Together, these chronic diseases and markers accounted for more than one fifth of all new cancers and more than one third of all cancer deaths in this study population, which was similar to the contribution of five major lifestyle risk factors combined -- smoking, insufficient physical activity, insufficient fruit and vegetable intake, alcohol consumption, and obesity.

The researchers also found that physical activity was associated with a nearly 40% reduction in the excess risks of cancer and cancer death associated with chronic diseases and markers. [Original study.]

A new study's results actually made me ask - this was a surprise? Of course more fit people have lower levels of chronic inflammation and smaller waist size, no matter their Body Mass Index (BMI) - which includes their weight. And the reverse is also true (lower fitness levels are associated with greater waist size and higher levels of chronic inflammation, no matter the BMI). Which means that being fit, no matter the weight, has health benefits. From Medical Xpress:

Low fitness is associated with larger waist size and higher degree of inflammation

Low fitness is associated with a larger waist size and a higher degree of inflammation, according to a study published January 17, 2018 in the open-access journal PLOS ONE by Anne-Sophie Wedell-Neergaard from the University of Copenhagen, Denmark, and colleagues.

Waist circumference can indicate the amount of excess fat found around the abdomen and previous studies have shown excess abdominal fat may increase the risk of chronic system inflammation and metabolic diseases. The authors of the present study sought to investigate the association between fitness and waist circumference as well as the association between fitness and low-grade inflammation, and whether there was a correlation with Body Mass Index (BMI).

The researchers analyzed the previously collected data of 10,976 individuals from The Danish National Health Examination Survey 2007-2008. These individuals took a maximal oxygen uptake (VO2max) test to assess their physical fitness. Their waist circumference, weight and height were measured, and blood samples were taken to measure their level of C-reactive protein, a nonspecific biomarker of low-grade inflammation.

The researchers found that higher levels of fitness were associated with a smaller waist circumference and a lower degree of inflammation independently of BMI. The researchers acknowledge that there are possible limitations that may affect the findings of the study, but overall the results suggest that increased fitness has the potential to reduce abdominal fat mass and inflammation which may improve metabolic health irrespective of BMI

A recent study's results give hope to those who haven't really exercised or been physically active as they've gone through middle-age (it's viewed as "sedentary aging") and wonder if this dooms them in some way. Is it too late to get benefits from starting to exercise now? Studies show that being sedentary (that is, not being physically active or exercising weekly) and in "poor physical fitness" in middle-age is a risk factor for later heart failure. This is because a consequence of "sedentary aging" is stiffness of the heart, specifically the left ventricle (thus a loss of "cardiac plasticity").

But the study found that after 2 years of an exercise program in (formerly) sedentary middle-aged adults, they improved their maximal oxygen uptake, decreased the heart's stiffness, and improved overall fitness. All good, even though it was a small study (only 53 people completed the study). So the bottom line is: No, it's not too late to start exercising. The heart has elasticity and can remodel itself if the exercise is started before age 65 and is done 4 to 5 times a week. The adults studied were both male and female, between the ages of 45 and 64,  and exercised or were physically active for a total of 150 to 180 minutes a week, which meant at least 30 minutes 4 or 5 times a week.

Looking at the study's exercise regimen, it's clear that a variety of exercises or physical activities (low, moderate, and high intensity) is necessary. Some of the time one should be active or exercise to a point of breaking a sweat and feeling the heart pump. This meant that over time the participants increased their exercise frequency, duration, and intensity. Think about it - as you get more fit, it takes more to get your heart pumping and to break a sweat, and you can handle more exercise. 

Unfortunately the "control group", who did a combination of yoga, balance, and strength training 3 times a week for 2 years did not show improvements in heart plasticity, maximal oxygen uptake, or in overall fitness.Yikes. Sooo...the study clearly shows it is worth getting off your butt and making the effort to exercise. Perhaps view it as brushing your teeth - a daily nuisance, but necessary for health. The researchers themselves stated "Exercise is medicine." From Science Daily:

Proper exercise can reverse damage from heart aging

Exercise can reverse damage to sedentary, aging hearts and help prevent risk of future heart failure -- if it's enough exercise, and if it's begun in time, according to a new study by cardiologists at UT Southwestern and Texas Health Resources. To reap the most benefit, the exercise regimen should begin by late middle age (before age 65), when the heart apparently retains some plasticity and ability to remodel itself, according to the findings by researchers at the Institute for Exercise and Environmental Medicine (IEEM), which is a collaboration between UT Southwestern Medical Center and Texas Health Presbyterian Hospital Dallas.

And the exercise needs to be performed four to five times a week. Two to three times a week was not enough, the researchers found in an earlier study..... The regimen included exercising four to five times a week, generally in 30-minute sessions, plus warmup and cool-down: One of the weekly sessions included a high-intensity 30-minute workout, such as aerobic interval sessions in which heart rate tops 95 percent of peak rate for 4 minutes, with 3 minutes of recovery, repeated four times (a so-called "4 x 4"). Each interval session was followed by a recovery session performed at relatively low intensity. One day's session lasted an hour and was of moderate intensity. (As a "prescription for life," Levine said this longer session could be a fun activity such as tennis, aerobic dancing, walking, or biking.) One or two other sessions were performed each week at a moderate intensity, meaning the participant would break a sweat, be a little short of breath, but still be able to carry on a conversation -- the "talk test.".... One or two weekly strength training sessions using weights or exercise machines were included on a separate day, or after an endurance session.

The more than 50 participants in the study were divided into two groups, one of which received two years of supervised exercise training and the other group, a control group, which participated in yoga and balance training.A t the end of the two-year study, those who had exercised showed an 18 percent improvement in their maximum oxygen intake during exercise and a more than 25 percent improvement in compliance, or elasticity, of the left ventricular muscle of the heart, Dr. Levine noted. He compared the change in the heart to a stretchy, new rubber band versus one that has gotten stiff sitting in a drawer. Sedentary aging can lead to a stiffening of the muscle in the heart's left ventricle, the chamber that pumps oxygen-rich blood back out to the body, he explained.

"When the muscle stiffens, you get high pressure and the heart chamber doesn't fill as well with blood. In its most severe form, blood can back up into the lungs. That's when heart failure develops," said Dr. Levine, who holds the S. Finley Ewing Chair for Wellness at Texas Health Dallas and the Harry S. Moss Heart Chair for Cardiovascular Research. Earlier research by UT Southwestern cardiologists showed that left ventricular stiffening often shows up in middle age in people who don't exercise and aren't fit, leaving them with small, stiff chambers that can't pump blood as well[Original study.]

For those who need convincing that lifestyle can contribute to development of cancer or its prevention, new medical research has once again supported the importance of lifestyle choices. A report from Australian researchers (with similar findings as a study in the US) stated: an estimated 38% of cancer deaths and 33% of cancer diagnoses could have been prevented with healthy lifestyle choices.

And what were the lifestyle choices that are linked to cancer?  The researchers list 20 separate things (in 8 broad groups) that are known to cause or are linked to cancer. They are: tobacco smoke (smoking or second-hand smoke), dietary factors (low-intake of fruit, non-starchy vegetables, and dietary fiber; and high intake of red and processed meat), overweight/obesity, alcohol, physical inactivity, solar ultraviolet radiation, certain infections (they list 7 infections, such as human papillomavirus, hepatitis B, hepatitis C), and reproductive factors (lack of breastfeeding, menopausal hormone therapy use, combined oral contraceptive use). Note that they found that the #1 most important lifestyle factor is tobacco smoke - and it accounted for about 23% of all preventable cancer deaths in Australia. From Medscape:

One Third of Cancer Deaths Could Be Prevented by Lifestyle

As we head into the festive season, many are looking forward to the tradition of "Eat, drink, and be merry." But as another research paper shows that more than a third of cancer deaths could be prevented by lifestyle, maybe a qualifier should be added:"celebration in moderation." The latest statistics come from Australia, where researchers note that 44,004 cancer deaths occurred in 2013. But an estimated 38% of these deaths and 33% of cancer diagnoses could have been prevented with healthy lifestyle choices, says a research team led by Louise Wilson, MEpi, at the QIMR Berghofer Medical Research Institute and the University of Queensland, Brisbane.

These cancer diagnoses and deaths were seen in Australians of all ages and are directly attributable to 20 known modifiable risk factors within eight categories that are established causes of cancer, the study authors say. The report is published in the February 2018 issue of the International Journal of Cancer.

Smoking was the leading cause of preventable cancer death in Australia in 2013 and accounted for 23% of all cancer deaths. ...Three other categories of modifiable risk factors — poor diet, overweight/obesity, and infections — accounted for 5% of cancer deaths each. In a fifth category, alcohol-related cancer accounted for 2.4% of deaths. Physical inactivity factors were responsible for 0.8% of cancer deaths, overexposure to ultraviolet radiation for 3.2% of cancer deaths, and, in the eighth category, reproductive or hormonal factors were linked to 0.4% of cancer deaths.

In the diet category, risk factors include low intake of fruit, nonstarchy vegetables, and dietary fiber and high intake of red and processed meat. In the infection category, seven cancer-causing agents, including human papillomavirus (associated with cancer of the vulva, vagina, penis, anus, oral cavity, and oropharynx) and Helicobacter pylori (noncardia stomach cancer), are included. Lack of breastfeeding, use of menopausal hormone therapy, and use of combined oral contraceptive use (breast and cervical cancer) are listed as preventable risk factors in the reproductive category.

These findings are in keeping with other research on the role of modifiable lifestyle-related risk factors in cancer prevention. As previously reported by Medscape Medical News, results from a large cohort study in the United States led researchers to conclude that 20% to 40% of cancer cases and related mortality could be prevented by not smoking, maintaining a healthy weight, and exercising regularly. In another report, results from a national online survey undertaken by the American Society of Clinical Oncology showed that, like their Australian counterparts, most US adults don't know alcohol and obesity are major risk factors for cancer[Original study.]

A dividing lung cancer cell. Lung cancer is associated with smoking. Credit: National Institute of Health (NIH). 

 

The message is clear from a recent study: older adults should get out and move, move , move (brisk walking is fine) - to lower the risk of early death. The older women engaging in the most moderate to vigorous activity had a 65% lower risk of early death during an average follow-up period of 2.3 years (when compared to the women with the least exercise).

How much exercise did the groups get? The least active had 6.8 minutes per day of moderate to vigorous exercise, and the most active had about 68 minutes/day of moderate to vigorous physical activity. The women wore a Fitbit type of device (an accelerometer) that measured their movements. Moderate to vigorous exercise was any movement that got the heart rate up a bit, made them sweat a little - and which could be brisk walking.

The study was done with older women (in their 70s), but one would think it also applies to men. Note: all-cause mortality means death from any cause (death in general). From Medscape:

Intense Exercise Tied to 65% Lower Death Risk in Older Women

Older women who engaged in the greatest amount of moderate to vigorous physical activity, such as brisk walking, were found to have a 65% lower risk of all-cause mortality compared with women who performed the least amount of such exercise, a new study reports. The researchers examined women in their early 70s in the Women's Health Study (WHS) who wore a triaxial accelerometer for 7 days to measure physical activity. The findings, by Dr I-Min Lee (Brigham and Women's Hospital, Boston, MA) and colleagues, were published November 6, 2017 in Circulation.

It's been known for a long time that physical activity is associated with lower mortality rates, Dr Lee told theheart.org | Medscape Cardiology.... Now that physical activity can be better measured using a research-grade triaxial accelerometer, the magnitude of the reduced risk of short-term death with recommended amounts of moderate to vigorous physical activity can be seen to be as strong as not smoking, Lee said. ... This study "reinforces the message that adults should strive to meet physical activity guidelines of 150 minutes of moderate or 75 minutes of vigorous exercise per week," Dr Alpa Patel (American Cancer Society, Atlanta, Georgia) who recently published a related article that showed benefits from walking told theheart.org | Medscape Cardiology.

From 2011 to 2015, 18,289 of 29,494 living women (63%) in the Women's Health Study agreed to participate in the current study.... The remaining 17,708 women were mailed a research-grade triaxial accelerometer (ActiGraph GT3X+, ActiGraph Corp) and asked to wear it on their hips for 7 days (but to take it off when sleeping or swimming) and then mail it back. 

The women spent a median of 8.4, 5.8, and 0.5 hours/day being sedentary, doing light physical activity, and doing moderate to vigorous physical activity, respectively. "The least active quartile were doing 8 minutes a day of moderate to vigorous . . . physical activity," Lee said, which was typically "brisk walking, anything that gets your heart rate up a little bit, gets you to sweat a little bit." The most active quartile did about 68 minutes/day of moderate to vigorous physical activity. During an average follow-up of 2.3 years, 207 women died. The total amount of physical activity was inversely related to the risk of all-cause mortality during follow-up, after adjustment for age and time spent wearing the device. 

Two studies (one in mice and one in humans) from researchers at the University of Illinois found that no matter what your diet - exercise changes the gut bacteria in a beneficial way. And when you go back to a sedentary lifestyle, your gut microbes change again and beneficial microbes such as short chain fatty acids (SCFAs), especially butyrates, decline. The effect was more pronounced in lean sedentary adults (as compared to obese sedentary adults).

Beneficial microbes that increased with exercise in humans were species of Faecalibacterium, Roseburia, Lachnospira, Lachnospiraceae, and Clostridiales. Faecalibacterium prausnitzii has been discussed in earlier posts as a beneficial keystone species in the gut (here, here, and here). What kind of exercises did they do? They did three supervised 30 to 60 minute moderate to vigorous intensity aerobic/endurance exercise sessions per week for 6 weeks, and they could use a cycle ergometer (stationary bicycle) or treadmill each session.

Besides beneficial microbial changes, 6 weeks of exercising resulted in improved body composition (total lean body mass, decreased body fat, increased bone mineral density), and an improvement in cardiorespiratory fitness. These changes reversed in everyone when they went back to 6 weeks of a sedentary lifestyle. Bottom line: get out and move, move, move. Your gut microbes and your body will thank you. From Science Daily:

Exercise changes gut microbial composition independent of diet, team reports

Two studies -- one in mice and the other in human subjects -- offer the first definitive evidence that exercise alone can change the composition of microbes in the gut. The studies were designed to isolate exercise-induced changes from other factors -- such as diet or antibiotic use -- that might alter the intestinal microbiota.

In the first study, scientists transplanted fecal material from exercised and sedentary mice into the colons of sedentary germ-free mice, which had been raised in a sterile facility and had no microbiota of their own. In the second study, the team tracked changes in the composition of gut microbiota in human participants as they transitioned from a sedentary lifestyle to a more active one -- and back again.

Recipients of the exercised mouse microbiota also had a higher proportion of microbes that produce butyrate, a short-chain fatty acid that promotes healthy intestinal cells, reduces inflammation and generates energy for the host. They also appeared to be more resistant to experimental ulcerative colitis, an inflammatory bowel disease.

In the human study, the team recruited 18 lean and 14 obese sedentary adults, sampled their gut microbiomes, and started them on an exercise program during which they performed supervised cardiovascular exercise for 30-60 minutes three times a week for six weeks. The researchers sampled participants' gut microbiomes again at the end of the exercise program and after another six weeks of sedentary behavior. Participants maintained their usual diets throughout the course of the study. Fecal concentrations of SCFAs, in particular butyrate, went up in the human gut as a result of exercise. These levels declined again after the participants reverted to a sedentary lifestyle.

The most dramatic increases were seen in lean participants, who had significantly lower levels of SCFA-producing microbes in their guts to begin with. Obese participants saw only modest increases in the proportion of SCFA-producing microbes. The ratios of different microbes in the gut also differed between lean and obese participants at every stage of the study, the researchers said. "The bottom line is that there are clear differences in how the microbiome of somebody who is obese versus somebody who is lean responds to exercise," Woods said. " [Original study in humans.]

It's reassuring to see that there are positive things one can do to maintain brain health as one ages. With normal aging, the brain typically shrinks a little with each passing decade  - starting from about the age of 40. But one recent Australian study, which reviewed the results of many other studies, found that exercise slows down this shrinkage in humans, specifically in the left hippocampus. That is, that aerobic exercise had a significant positive effect on the volume of the left hippocampus. This matches the result of animal studies.

The researchers pointed out that some studies found increases also in other parts of the human brain from exercise (e.g. in the white matter), but that they did not look at and review those studies. [See posts on research.] The good news is that positive effects were from exercise programs generally lasting less than 12 months. But it is unknown which type of exercise is best, or whether it is general "activity level and movement" that is most important. Bottom line: Get out there and move, move, move for brain health. And for cardiorespiratory fitness. It's all linked and it's all good. From Medical Xpress:

Exercise maintains brain size, new research finds

Aerobic exercise can improve memory function and maintain brain health as we age, a new Australian-led study has found. In a first of its kind international collaboration, researchers from Australia's National Institute of Complementary Medicine at Western Sydney University and the Division of Psychology and Mental Health at the University of Manchester in the UK examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions.

Brain health decreases with age, with the average brain shrinking by approximately five per cent per decade after the age of 40. Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent.

The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions. The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66. The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week.

Overall, the results – published in the journal NeuroImage– showed that, while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans.

"When you exercise you produce a chemical called brain-derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain," Mr Firth said. "Our data showed that, rather than actually increasing the size of the hippocampus per se, the main 'brain benefits' are due to aerobic exercise slowing down the deterioration in brain size. In other words, exercise can be seen as a maintenance program for the brain.".... Interestingly, physical exercise is one of the very few 'proven' methods for maintaining brain size and functioning into older age.

So you finally lost weight by diligently dieting, but now the issue is how to keep the weight from creeping back up again. Keeping strict watch over what you eat (basically continuing to diet)? Or exercising? Or...? Another issue muddying the waters is that a big weight loss also lowers the metabolism rate - something that occurred to former participants of the reality TV show The Biggest Loser. They lost enormous amounts of weight during the 30 week competition (over 100 pounds on average), but 6 years later much of the weight was regained, and they were burning hundreds fewer calories each day at rest. So they had become metabolically much slower over time.

A study looking at 14 former participants of The Biggest Loser 6 years after the show found that a large persistent increase in physical activity was essential for long-term maintenance of weight loss. Those who regained the least weight were the most active, and vice versa. On the other hand, food intake (keeping calorie intake low) wasn't the most important. How much of an increase in physical activity was needed to maintain the weight loss? Researchers found that an increase of about 80 minutes of daily moderate activity (such as brisk walking) or 35 minutes of daily vigorous activity was needed. From Medscape:

The Biggest Loser: Physical Exertion Is Key to Keeping Weight Off

Persistent increased physical activity is likely essential for long-term maintenance of weight loss, new research from participants in the US TV reality show The Biggest Loser suggests.... Using objective measures for both energy intake and physical activity in 14 former Biggest Loser contestants 6 years after they participated in the competition, Dr Kerns and colleagues found that those who had regained the least weight were the most active, and vice versa. Food intake, on the other hand, had very little effect on long-term weight-loss maintenance.

Asked to comment, Eric Ravussin, PhD, Boyd Professor at Louisiana State University, Baton Rouge, and coeditor of Obesity, told Medscape Medical News that the data align with those of follow-ups to major trials — including the Diabetes Prevention Program and the Action for Health Diabetes (Look AHEAD) study as well as with the National Weight Control Registry — of thousands of people who have lost at least 30 pounds and kept them off for at least a year. "The successful losers…all report high levels of physical activity" for weight maintenance, in contrast to weight loss, for which caloric deficit plays a far greater role, Dr Ravussin noted.

The reason for the difference between what works for weight loss vs maintenance, he said, probably has a lot to do with metabolic adaptation. This was the subject of another Biggest Loser paper published in Obesity in 2016, in which a person's metabolism slows down in response to a large drop in weight, making weight-loss maintenance difficult without an extra "push" from exercise, he explained.

The subjects in the new study were 14 participants with class III obesity who participated in a single season of The Biggest Loser, during which they underwent an intensive 30-week diet and exercise program and lost an average of 60 kg. Most regained weight after the program ended, although the degree of regain was highly variable. The median weight loss after 6 years was 13%. Seven subjects above the median weighed 24.9% less than baseline (maintainers) while the seven below the line (regainers) weighed 1.1% above their baseline. The maintainers had significantly greater increases in physical activity from baseline compared with the regainers..... that 35 minutes a day of intensive exercise, or 80 minutes of moderate activity, would roughly approximate the calorie expenditures among the maintainers.

A newly published study suggests that exercising an hour or more per week could lower the incidence of depression. The study followed 33,000 adults in Norway  for 11 years, and found that an hour or more of weekly exercise was associated with 12% fewer cases of developing depression. But note that it didn't prevent anxiety. Interestingly, the researchers found that "regular leisure-time exercise of any intensity" had these positive effects - it doesn't have to be aerobic or incredibly strenuous exercise. Exercise is associated with a number of biological changes that could have an impact on mental health. From Science Daily:

One hour of exercise a week can prevent depression

A landmark study led by the Black Dog Institute has revealed that regular exercise of any intensity can prevent future depression -- and just one hour can help. Published in the American Journal of Psychiatry, the results show even small amounts of exercise can protect against depression, with mental health benefits seen regardless of age or gender.

In the largest and most extensive study of its kind, the analysis involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years. The international research team found that 12 percent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week.

A healthy cohort of participants was asked at baseline to report the frequency of exercise they participated in and at what intensity: without becoming breathless or sweating, becoming breathless and sweating, or exhausting themselves. At follow-up stage, they completed a self-report questionnaire (the Hospital Anxiety and Depression Scale) to indicate any emerging anxiety or depression.

Results showed that people who reported doing no exercise at all at baseline had a 44% increased chance of developing depression compared to those who were exercising one to two hours a week. However, these benefits did not carry through to protecting against anxiety, with no association identified between level and intensity of exercise and the chances of developing the disorder. [Original article.]