Are Meal Timing and Frequency Important for Weight Loss?

These are age-old debates, which is better for weight loss…

… having frequent small meals vs. fewer large meals, eating breakfast vs. skipping breakfast, largest first meal vs. largest last meal.

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Eating frequently is often recommended as a weight loss strategy. Supposedly, eating more often reduces hunger, and therefore total calorie intake, which results in weight loss.

WHAT DOES THE RESEARCH SHOW?

Some observational studies have suggested that people who consumed more snacks (ate more frequently) were less likely to be obese. However, other large prospective studies have shown that frequent snacking leads to weight gain, increased abdominal and liver fat, and increased risk of type 2 diabetes.

Intermittent fasting, or going longer periods of time without eating, has shown promise in prolonging life spans and positively affecting glucose tolerance, insulin sensitivity, and incidence of type 2 diabetes. With a shorter allowed eating window, reduced meal frequency is usually involved.

The effect of meal frequency (number of meals per day) in humans does not yet have strong clinical evidence. Macronutrient (protein, fat, carbohydrate) quality is also important to consider. There is a large body of evidence suggesting that a higher protein intake, consumed more frequently, may be beneficial in overweight subjects.

Data on meal timing (when meals are consumed) are better established than meal frequency. Some studies suggest that eating meals later in the evening may adversely influence weight loss success. It has also been observed that those who eat breakfast regularly may be protected against weight gain but reducing overall calorie intake at the end of the day.

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WHAT DO THE SEVENTH DAY ADVENTISTS TEACH US?

Yes, this study drew on data from a set of over 50,000 non-smoking Adventist subjects throughout the US and Canada. Take these results how you wish as Adventists are known for recommending vegetarianism (an estimated 35% are veg*ns) and following kosher laws (abstinence from pork, shellfish), discourages use of alcoholic beverages, tobacco and illegal drugs, and some avoid caffeine.

  • Eating 1-2 meals/day was associated with a relative decrease in body weight compared with 3 meals/day. Also, participants who ate >3 meals/day had a higher body weight with more meals and snacks corresponding to an ever increasing body weight.
  • Those with long overnight fasts had relatively lower body weights than those with medium overnight fasts and both had lower body weights compared to short overnight fasts.
  • Breakfast eaters had lower relative body weights than those who skipped breakfast.
  • Eating the largest meal at breakfast corresponded with a lower relative body weight than those who eat their largest meal at lunch or dinner.

These findings are consistent with other large prospective studies that found that frequent eating/snacking is associated with a greater risk of weigh gain or of being overweight or obese, possibly due to unhealthy food choices and uncontrolled energy balance.

Eating two large meals per day at breakfast and lunch and having a longer overnight fast every day has been a historically recommended Adventist meal pattern. Benefits, risks, and effects on protein synthesis and energy balance need to be further studied in large-scale long-term studies as well as randomized clinical trials.

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BUT, WHY!?

Although the exact mechanisms behind meal frequency and meal timing and the regulation of body weight are not well know, there are several potential pathways.

  1. Satiety hormones – leptin, ghrelin. Hunger is intrinsically highest in the evening which promotes the tendency to eating the largest meal late in the day. However, eating a large breakfast reduces hunger and cravings for sweets and fats as well as post-meal ghrelin concentrations. Suppression of this ghrelin release depends on insulin – frequent eating seems to disrupt this relationship in a similar way as other insulin-resistant states.
  2. Meal frequency and timing and reset and amplify circadian clocks and  genes that control metabolic pathways, which are disrupted in metabolic disease and obesity. Both feeding and fasting change genetic transcription rates and the circadian phase of these genes. Time-restricted feeding seems to improve circadian rhythms of key metabolic regulators like mTOR, CREB, and AMPK.
  3. Some experiments have suggested that intermittent fasting and reduced meal frequency is associated with less oxidative damage and higher stress resistance which may prevent the development of obesity through improved adipose tissue signaling and less increase of fat depots.
  4. Regular breakfast consumption seems to increase satiety, reduce total caloric intake, improve overall diet quality (higher fiber, more nutrient dense foods), reduce blood lipids, and improve insulin sensitivity and glucose tolerance at subsequent meals. Those who eat breakfast have also shown to possibly have a higher amount of physical activity, increased adipose tissue insulin sensitivity, and more stable blood sugar levels during the day.
SOURCE
Kahleova et al. “Meal Frequency and Timing Are Associated with Changes in Body Mass Index in Adventist Health Study 2”. J Nutr 2017;147:1722-8. doi: https://doi.org/10.3945/jn.116.244749.
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