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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.

 The following is a study with weird results, really weird results. And it makes me think of all the times I've heard people joke: "just smelling food makes me gain weight", because we all knew it wasn't true. But what if it was true? .... The results of this study done in mice are that actually smelling the food one eats results in weight gain, and not being able to smell the food results in weight loss - even if both groups eat the same amount of food. And the "supersmellers" (those with a "boosted" sense of smell) gained the most weight of all.

What? How could that be? Yes, the study was done in mice, but perhaps it also applies to humans (the researchers think so). The researchers think  that the odor of what we eat may play an important role in how the body deals with calories - if you can't smell your food, you may burn it rather than store it. In other words, a link between smell and metabolism. Excerpts from Science Daily:

Smelling your food makes you fat

Our sense of smell is key to the enjoyment of food, so it may be no surprise that in experiments at the University of California, Berkeley, obese mice who lost their sense of smell also lost weight. What's weird, however, is that these slimmed-down but smell-deficient mice ate the same amount of fatty food as mice that retained their sense of smell and ballooned to twice their normal weight. In addition, mice with a boosted sense of smell—super-smellers—got even fatter on a high-fat diet than did mice with normal smell.

The findings suggest that the odor of what we eat may play an important role in how the body deals with calories. If you can't smell your food, you may burn it rather than store it. These results point to a key connection between the olfactory or smell system and regions of the brain that regulate metabolism, in particular the hypothalamus, though the neural circuits are still unknown. The new study, published this week in the journal Cell Metabolism, implies that the loss of smell itself plays a role, and suggests possible interventions for those who have lost their smell as well as those having trouble losing weight. "Sensory systems play a role in metabolism. Weight gain isn't purely a measure of the calories taken in; it's also related to how those calories are perceived," said senior author Andrew Dillin,...

The smell-deficient mice rapidly burned calories by up-regulating their sympathetic nervous system, which is known to increase fat burning. The mice turned their beige fat cells—the subcutaneous fat storage cells that accumulate around our thighs and midriffs - into brown fat cells, which burn fatty acids to produce heat. Some turned almost all of their beige fat into brown fat, becoming lean, mean burning machines. In these mice, white fat cells—the storage cells that cluster around our internal organs and are associated with poor health outcomes—also shrank in size. The obese mice, which had also developed glucose intolerance - a condition that leads to diabetes—not only lost weight on a high-fat diet, but regained normal glucose tolerance.

On the negative side, the loss of smell was accompanied by a large increase in levels of the hormone noradrenaline, which is a stress response tied to the sympathetic nervous system. In humans, such a sustained rise in this hormone could lead to a heart attack.

Dillin and Riera developed two different techniques to temporarily block the sense of smell in adult mice. .... In both cases, the smell-deficient mice ate as much of the high-fat food as did the mice that could still smell. But while the smell-deficient mice gained at most 10 percent more weight, going from 25-30 grams to 33 grams, the normal mice gained about 100 percent of their normal weight, ballooning up to 60 grams. For the former, insulin sensitivity and response to glucose - both of which are disrupted in metabolic disorders like obesity - remained normal.

Mice that were already obese lost weight after their smell was knocked out, slimming down to the size of normal mice while still eating a high-fat diet. These mice lost only fat weight, with no effect on muscle, organ or bone mass. The UC Berkeley researchers then teamed up with colleagues in Germany who have a strain of mice that are supersmellers, with more acute olfactory nerves, and discovered that they gained more weight on a standard diet than did normal mice[Original study.]

 Of course eating meals prepared at home is healthier! The study results - that people who often consume meals prepared at home are less likely to suffer from type 2 diabetes than those who consume such meals less frequently shouldn't be surprising. The researchers attributed the higher incidence of type 2 diabetes to weight gain in those eating fewer meals prepared at home, but there are other things going on also.

Restaurant and fast food meals tend to have very large portions, frequently with rich sauces, and the meal choices tend to be heavy on fat and salt. The meals can be high in calories, contain many artificial ingredients, and may be low in nutritional quality (and so also not nourishing the beneficial gut microbes that are linked to health). At home you can limit portions, control the food ingredients, and eat only healthy foods (see earlier post on this). From Science Daily:

Enjoying meals prepared at home: Short-cut to avoiding diabetes?

People who often consume meals prepared at home are less likely to suffer from type 2 diabetes than those who consume such meals less frequently, according to  new epidemiological research reported by Qi Sun, of the Harvard T.H. Chan School of Public Heath, Boston, USA and colleagues as part of PLOS Medicine's special issue on Preventing Diabetes.

Internationally, there is an increasing tendency for people to eat out, and this could involve consumption of fast food, for example. Concerns have been raised that such people have a diet that is rich in energy but relatively poor in nutrients -- this could lead to weight gain which is, in turn, associated with an increased risk of type 2 diabetes.

Sun and colleagues employed large prospective data sets in which US health professionals -- both men and women--were followed-up for long periods, with rigorous collection of data on health indicators, including self-reported information on eating habits and occurrence of diabetes. The results were corrected for various known factors that could affect dining habits, including marital status. All in all, the study analyzed 2.1 million years of follow-up data.

The findings indicate that people who reported consuming 5-7 evening meals prepared at home during a week had a 15% lower risk of type 2 diabetes than those who consumed 2 such meals or fewer in a week. A smaller, but still statistically significant, reduction was apparent for those who reported consuming more midday meals prepared at home. Other analyses suggest that less weight gain could partially explain the reported reduction in occurrence of type 2 diabetes in those often eating meals prepared at home.

Two studies about blood pressure and how it can be easily changed without medications. From Science Daily:

Small weight gain can raise blood pressure in healthy adults

Gaining a few pounds can increase blood pressure in healthy adults, researchers report. Increased fat inside the abdomen led to even larger increases in blood pressure, their study results showed. Many people understand the health dangers of large amounts of extra body weight, but researchers in this study wanted to see the impact of a small weight gain of about five to 11 pounds.

At the beginning of the eight-week study, a 24-hour monitor tested the blood pressure of 16 normal weight people. Their results were compared to 10 normal weight, healthy people who maintained the same weight over the eight weeks. Researchers found: -Those who gained weight had a systolic blood pressure (top number) increase from an average 114 mm Hg to an average 118 mm Hg. -Those who gained more weight inside their abdomen had a greater blood pressure increase. -A five to 11 pound weight gain didn't change cholesterol, insulin or blood sugar levels. The study was conducted in healthy people ages 18-48. 

From Science Daily:

Restricting calories may improve sleep apnea, blood pressure in obese people

Restricting calories may improve sleep apnea and reduce blood pressure in obese adults. Those who restricted their calories had higher levels of oxygen in their blood and a greater reduction in body weight, a study has demonstrated.

 "Losing weight was most likely the key to all the benefits observed in the calorie-restricted group. A greater reduction in systolic blood pressure can be explained, at least partially, by the reduction in body weight that was associated with reduction in obstructive sleep apnea severity and sympathetic nervous system activity." Systolic blood pressure is the top number in a blood pressure reading, which measures the force of the blood in the arteries when the heart is contracted.

Another study showing the benefits of eating berries. From the January 23, 2014 Science Daily:

Lingonberries halt effects of high-fat diet

Lingonberries almost completely prevented weight gain in mice fed a high-fat diet, a study at Lund University in Sweden has found -- whereas the 'super berry' açai led to increased weight gain. The Scandinavian berries also produced lower blood sugar levels and cholesterol.

Some of the mice were fed a low-fat diet, while the majority of the animals were fed a diet high in fat. They were then divided into groups, where all except a control group were fed a type of berry -- lingonberry, bilberry, raspberry, crowberry, blackberry, prune, blackcurrant or açai berry.

When the mice were compared after three months, it could be observed that the lingonberry group had by far the best results. The mice that had eaten lingonberries had not put on more weight than the mice that had eaten a low-fat diet -- and their blood sugar and insulin readings were similar to those of the 'low-fat' mice. Their cholesterol levels and levels of fat in the liver were also lower than those of the animals who received a high-fat diet without any berries.

Blackcurrants and bilberries also produced good effects, although not as pronounced as the lingonberries. The açai berries, on the other hand, came last, although they had actually been included in the study for the opposite reason -- the researchers wanted to see how well the Nordic berries would do in comparison with the Brazilian 'super berry'.

The good results from lingonberries may be due to their polyphenol content, according to the researchers. They will now continue to work on understanding the molecular mechanisms involved in the effect of the lingonberries. They will also see whether the effect can be observed in humans.