Big breakfast helps obese subjects suppress appetite in weight loss study
As the research continues to build around fasting diets and time-restricted eating, we can expect to gain a clearer understanding of when might be the best times to eat and why. A study has shed interesting new light on this topic by examining the effects of “front-loaded” diets that hinge on a heavy breakfast, finding that while they offer no real weight-loss potential, they may well suppress our appetite throughout the day.
We’ve seen research fill important gaps in our knowledge around the pros and cons of different dieting regimes, including studies finding that simple caloric restriction is more effective for weight loss than fasting, and some that even point to the anti-aging potential of eating exclusively during the daytime.
In investigating so-called “front-loaded” calorie consumption, scientists at Scotland’s University of Aberdeen sought to explore the idea that eating the bulk of your food earlier in the day sees you more readily shed fat. This concept may be best known to some through the old adage “eat breakfast like a king, lunch like a prince, and dinner like a pauper,” and posits that by tying in with the circadian rhythm, or body clock, these eating habits enable our metabolism to burn calories more efficiently.
“There are a lot of myths surrounding the timing of eating and how it might influence either body weight or health,” says senior author Professor Alexandra Johnstone, study author. “This has been driven largely by the circadian rhythm field. But we in the nutrition field have wondered how this could be possible. Where would the energy go? We decided to take a closer look at how time of day interacts with metabolism.”
To do so, Johnstone and her team enlisted 30 overweight or obese subjects, 16 male and 14 female, who were randomly split into a morning-loaded diet group, or an evening-loaded diet group. Both diets included a roughly equal balance of protein, carbohydrates and fat, and were undertaken for a period of four weeks before a week-long washout period of balanced caloric intake across the day. The subjects then switched and completed the opposite diet for a four-week period.
The scientists tracked the energy expenditure of the subjects through what’s called the double-labeled water method, which measures the body’s turnover of hydrogen and oxygen. The scientists found no difference between the two diets in terms of energy expenditure or weight loss, with the subjects shedding an average of just over 3 kg (7 lb) during each of the four-week diet programs.
Among the secondary measures, however, the scientists tracked the effects of meal timing on appetite control, something they say is under-explored as earlier studies have often lacked temporal measures for appetite. They did so by using visual analog scales to measure the subjective appetite of subjects at hourly intervals, from the time of waking until bedtime for three consecutive days, and at 30-minute intervals in the lab on a testing day. Those in the front-loaded diet group reported significantly lower hunger levels throughout the day.
“The participants reported that their appetites were better controlled on the days they ate a bigger breakfast and that they felt satiated throughout the rest of the day,” Johnstone says. “This could be quite useful in the real-world environment, versus in the research setting that we were working in.”
The study size is small and the researchers note that it was carried out in free-living conditions rather than a tightly-controlled laboratory setting, but it does offer some food for thought. They plan to follow up the work with further studies on the metabolism of shift-workers, while intermittent fasting is another dieting regime they’d like to apply their methods to.
“One thing that’s important to note is that when it comes to timing and dieting, there is not likely going to be one diet that fits all,” Johnstone concludes. “Figuring this out is going to be the future of diet studies, but it’s something that’s very difficult to measure.”
The research was published in the journal Cell Metabolism.
Source: University of Aberdeen