Various intermittent fasting schemes have recently been slipping into the perilous realm of "fad diets" but a compelling, growing body of scientific research is starting to suggest that some kind of controlled fasting pattern could have beneficial health and weight loss effects. New research from the University of Illinois at Chicago has examined a form of time-restricted eating known as the 16:8 diet and the small study has found it could indeed be an effective form of weight loss.
The most popular recent form of intermittent fasting has been the 5:2 diet. This eating strategy involves a normal (albeit still healthy) diet for five days of the week, and extreme calorie restriction for the remaining two days. Much of the recent research into intermittent fasting has concentrated on examining the efficacy of strategies like the 5:2 diet, and the results have generally been promising, with reductions in body fat and insulin levels.
A newer model for intermittent fasting has emerged over the last few years and some are suggesting it is much easier to maintain than the 5:2 strategy. This method is called 16:8 and it essentially limits a person's food intake to an eight-hour stretch of the day. So, ultimately a person is fasting for a minimum of 16 hours every day.
Research into this specific kind of eating pattern is still in its nascent stages but the early evidence is promising. A 2016 study into the effects of a 16:8 dietary pattern on young resistance-trained men found after just eight weeks there were improvements in a variety of health-related biomarkers and a decrease in fat mass.
This latest study from the University of Illinois at Chicago is the first to focus specifically on the 16:8 diet's effect on weight loss in obese individuals. The study was small, consisting of only 23 obese subjects with an average age of 45. The subjects were matched against a historical control group from a previous weight loss trial by the same research team.
The subjects in the study were not given controlled diets but rather told to continue eating as normal but to limit their food intake to between the hours of 10 am and 6 pm. After 12 weeks the results interestingly showed that the 16:8 group seemed to instinctively have reduced their overall daily caloric intake by about 300 calories. Their overall body weight had also dropped by around three percent, compared to the historical control group.
Other studies examining alternate day fasting or the 5:2 strategy find weight decreases of four to six percent after 12 weeks on average, so this new data does suggest that, comparably, the 16:8 diet is not as immediately effective for weight loss as those other plans. But, the researchers do note that this eating strategy may be more sustainable on a long-term basis.
"The results we saw in this study are similar to the results we've seen in other studies on alternate day fasting, another type of diet," says corresponding author on the study Krista Varady, "but one of the benefits of the 16:8 diet may be that it is easier for people to maintain. We observed that fewer participants dropped out of this study when compared to studies on other fasting diets."
This study has an immense amount of limitations making it difficult to leap to more general conclusions about the efficacy of the diet. The cohort self-reported both eating times and meal volumes, which the researchers admit may not be an optimal way to get good data. There are also significant questions over what differences either a shorter eating period, or a differently placed eating window would make. For example, is a six-hour eating window between 8 am and 2 pm a more effective strategy for weight loss than an eight hour window between midday and 8 pm?
A decent amount of recent research is making clear that when you eat could be just as important as what you eat. Of course, globally, different people and cultures have different eating patterns, so there may not be one rule that works for all, but generally those who eat more of their caloric intake earlier in the day seem to have greater weight loss abilities and better blood sugar levels.
More research is obviously necessary before we can have a better scientific perspective on the broader effects different fasting patterns have on our overall metabolism, but the preliminary evidence is certainly promising. These types of intermittent fasting diets may be sitting on the precipices of becoming a cultural "fad" but there does seem to be a growing body of evidence pointing to beneficial health effects.
The new study was published in the journal Nutrition and Healthy Aging.
Source: UIC Today
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