While epidemiological reports have suggested a favourable relationship between increased meal frequency, weight and metabolic health, there is a lack of evidence from controlled intervention trials to support the same conclusion, warn researchers writing in Biochimie.
The review of the metabolic impacts of altering meal frequency and timing evidence, led by senior author Associate Professor Leonie Heilbronn at the University of Adelaide, warns that controlled trials have been limited in sample size and duration, and “have shown little or no beneficial impact of increased meal frequency on body weight and health under either eucaloric or hypocaloric conditions.”
“Further, increased meal frequency was detrimental to metabolic health under conditions of energy excess,” they noted, adding that such findings are ‘of concern’ since rising rates of obesity indicate that most of the population eat to excess.
Heilbronn and her team also noted that there is emerging evidence that the timing of food intake plays a much more important role in metabolism than previously thought – leading to recent suggestions that when we eat could be a more important factor than the frequency of meals.
“Eating late in the day or at night disrupts circadian rhythms, and may have adverse effects on weight and health,” they warned.
Now, Heilbronn and her colleagues are planning to follow up the review findings with a new intervention trial to test the importance of timing what you eat in setting up the right biological processes to maintain optimal metabolism and healthy body weight.
“Studies in mice show that restricting the timing of what is eaten rather than necessarily the content can lead to maintaining a healthy metabolism,” she noted. “But in people there’s not yet a lot of evidence. We’re doing this study to see whether the timing factor also has an impact on health in humans.”
New study on snack timing
Heilbronn’s new study aims to look for further evidence in humans, and in particular to determine whether eating at night is detrimental on health – building on suggestions that just like sleep/wake cycles, metabolism may also have a circadian rhythm.
“Our gut, fat cells and liver all function differently during the night compared to the day,” explained Heilbronn. “Maybe you’re just not supposed to see nutrients during the night time.”
The upcoming study will compare three groups of subjects to investigate how the timing of eating can change metabolism.
Participants will alter their food intake to take place from 7am-3pm, or 1pm-9pm, or maintain a more regular eating pattern of three meals a day.
“We will assess diabetes risk factors through assessing blood glucose levels, as well as cholesterol and triglycerides,” said the lead researcher. “We’re currently looking to recruit overweight men as volunteers.”
Published online ahead of print, doi: 10.1016/j.biochi.2015.07.025
“Metabolic impacts of altering meal frequency and timing – Does when we eat matter?”
Authors: Amy T. Hutchisona, Leonie K. Heilbronn