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Increasing the Length of the Nighttime Fast May Have Health Benefits

Lately there has been discussion about "intermittent fasting" (on some days or time periods) and possible health benefits. Now an interesting small study has been published that found health benefits to eating as usual, but only within a restricted time frame.

Thirteen healthy, but overweight individuals were either assigned to an "eat normally as usual" group or a group that "ate only within a restricted time frame" - that is, they ate breakfast 1.5 hours or more later and supper 1.5 hours earlier (this was their last food of the day). After 10 weeks those eating only within the restricted time frame had lost body fat ( a health benefit), but not weight. However, there were complaints that eating within a restricted time frame was hard to do because it interfered with social events and family meals. Bottom line: lengthening the daily fast (from dinner to breakfast) without changing foods eaten appears to have health benefits. (Posts on "minifasting", Fasting Mimic Diet, fasting, 5 day calorie restriction). From Science Daily:

Changes in breakfast and dinner timings can reduce body fat

Modest changes to breakfast and dinner times can reduce body fat, a new pilot study in the Journal of Nutritional Sciences reports. During a 10-week study on 'time-restricted feeding' (a form of intermittent fasting), researchers led by Dr Jonathan Johnston from the University of Surrey investigated the impact changing meal times has on dietary intake, body composition and blood risk markers for diabetes and heart disease. 

Participants were split into two groups -- those who were required to delay their breakfast by 90 minutes and have their dinner 90 minutes earlier, and those who ate meals as they would normally (the controls). Participants were required to provide blood samples and complete diet diaries before and during the 10-week intervention and complete a feedback questionnaire immediately after the study. Unlike previous studies in this area, participants were not asked to stick to a strict diet and could eat freely, provided it was within a certain eating window. This helped researchers assess whether this type of diet was easy to follow in everyday life.

Researchers found that those who changed their mealtimes lost on average more than twice as much body fat as those in the control group, who ate their meals as normal. If these pilot data can be repeated in larger studies, there is potential for time-restricted feeding to have broad health benefits.

Although there were no restrictions on what participants could eat, researchers found that those who changed their mealtimes ate less food overall than the control group. This result was supported by questionnaire responses which found that 57 percent of participants noted a reduction in food intake either due to reduced appetite, decreased eating opportunities or a cutback in snacking (particularly in the evenings). It is currently uncertain whether the longer fasting period undertaken by this group was also a contributing factor to this reduction in body fat.

As part of the study, researchers also examined if fasting diets are compatible with everyday life and long term commitment. When questioned, 57 percent of participants felt they could not have maintained the new meal times beyond the prescribed 10 weeks because of their incompatibility with family and social life. However, 43 per cent of participants would consider continuing if eating times were more flexible.

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