More Proof “Eating Small Meals More Frequently” Does Not Boost Metabolism
Jan 2013 28
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It's long been a maxim in the weight loss arena that eating frequent small meals throughout the day somehow "speeds up your metabolism" and increases fat loss. The belief is so widespread that most people simply assume it's true and never ask to see any supporting research.

Which is a pity, because if they did they'd soon learn the multiple-small-meals theory of weight loss is complete rubbish.

In Chapter 3 of The Fat Loss Bible, I compiled all the clinical trial studies I could find comparing low-frequency meal plans with high-frequency meal plans. The results overwhelmingly show that whether you eat 1, 3, or 6 meals per day, it doesn't make a whit of difference to weight loss - the overriding determinant of how much chub you lose is, as always, the calorie deficit you establish during your cutting phase.

A new study by Dutch researchers at the Maastricht University Medical Center further contradicts the eat-smaller-meals-more-often theory[1].

The researchers recruited twelve non-overweight males (average body fat % = 14.1) who randomly received the same diet with a low meal frequency (3 meals daily) or a high meal frequency (14 meals daily).

Yeah, I know what you're all thinking: "What kind of a tosser eats fourteen times a day in real life?"

Someone with way too much time on their hands, I suppose. But keep in mind one of the earliest studies on this subject compared a 3-meal regimen with a 17-meal per day regimen! That 1989 study has been cited ad nauseum in support of high meal frequencies, even though it had nothing to do with weight loss. The study simply found that the utterly impractical 17-meal regimen lowered serum insulin (but did not improve glycemic responses to a subsequent test meal or OGTT) and lowered total and LDL cholesterol. Given the lack of improvement in underlying glycemic function and that the cholesterol hypothesis is the biggest wank in the history of modern medicine, what we can safely conclude from the 1989 study is that eating 17 meals per day is a colossal waste of time.

Anyway, back to the study at hand. While the meal frequency varied greatly between the two test diets, both contained 15% protein, 30% fat, and 55% carbohydrates. The subjects were fed maintenance-calorie intakes based on their individual energy requirements.

The 3-meal diet consisted of breakfast at 8am, lunch at noon, and dinner at 5pm. In the high-frequency diet, meals were consumed every hour from 8am until 11pm.

Unlike most of the studies I discuss in The Fat Loss Bible, this was a very short study (36 hours on each diet inside a respiration chamber) that did not examine actual changes in body weight, but changes in glycemia and metabolic rate.

To examine the diets' effects on metabolism, the subjects entered the respiration chamber at 8pm and finished the intervention 36 hours later at 8 am. Physical activity was standardized (3 x 15 minute bouts of stepping).

Have you ever wondered what it's like inside a respiration chamber? Probably not, but I'll tell you anyway. The respiration chamber was a 14 m3 room furnished with a bed, chair, table, television, radio, telephone, computer, washbowl, intercom, and a deep-freeze dunny (Australian for toilet, mate!)

This next section might sound a bit dry but should give you some idea of the length to which the researchers went to keep everything nice and controlled and standardized. Air locks were used for exchange of food and urine. Energy expenditure was determined from the measurements of O2 consumption, CO2 production, and urine nitrogen excretion. The chamber was ventilated with fresh air at a rate of 70–80 l/min, and this ventilation rate was measured with a dry gas meter. The concentrations of O2 and CO2 were measured using a paramagnetic O2 analyser and an infrared CO2 analyzer. Ingoing air was analyzed one every 15 minutes and outgoing air once every 5 minutes. The gas sample to be measured was selected by a computer, which also stored and processed the data. Last but not least, physical activity was monitored using a radar system.

To measure satiety on the two diets, the subjects completed questionnaires just before, 30, and 60 minutes after consumption of the three experimental meals in the 3-meal diet, and the next morning at 8am. On the high-frequency diet, the questionnaires were completed at the same time-points.

Blood was also drawn just before ingestion of the first meal (baseline), 30 minutes post-meal, and subsequently every hour until 9.30pm to determine plasma insulin, glucose, free fatty acids, and triglycerides.

The Results

While total energy expenditure was not significantly different between the two diets, sleeping metabolic rate and dietary induced thermogenesis were each non-significantly higher on the low-frequency diet. When the latter two were combined it translated to a statistically significant increase in resting metabolic rate: 2044 versus 1925 calories/day on the low- and high-frequency diets, respectively. No previous meal frequency study has observed such an increase, which as the researchers note may be due to the fact that none of these other studies featured such extreme differences in meal frequency.

As noted, few people eat over a dozen times a day, and even if they did, whether any short-term reduction in RMR would hold up over the longer term is unknown. What this study does provide is yet more confirmation that increasing your meal frequency in the hope of achieving some kind of magical boost in metabolism is a total waste of time.

Before people jump to the wrong conclusion, I need to state quite clearly that I'm not against eating more than 3 meals per day.  While I do think regular consumption of 14-17 meals per day would indicate some kind of mental disorder, there are situations in which eating 4-6 meals daily is highly beneficial. I myself routinely average 5 meals per day - it's the only way I can shovel enough calories down my gullet to keep my weight up. If you're a hardgainer who's trying to acquire some extra muscle mass, it's going to be rather difficult to consume the 4,000 or more calories you likely need each day in 3 square meals.

Another reason given for following multiple meal regimens is allegedly improved glycemic control, but previous research is mixed on this outcome. In this study, the low-frequency diet showed significantly higher peaks and lower troughs for glucose and insulin levels, as would be expected. However, the area under the curve of 24 hour glucose (a measure of total blood glucose exposure, if you will) was significantly lower in the low-frequency diet, suggesting superior glycemic control. The  AUC of insulin was not significantly different between the two diets.

As for the satiety questionnaires, prospective food consumption and thirst ratings were significantly reduced, and satiety and fullness ratings significantly increased on the low-frequency diet as compared with the high-frequency diet.

The Bottom Line

The claim that eating smaller meals more frequently will aid fat loss by boosting your metabolism is a load of cobblers.


1. Munsters MJM, Saris WHM. Effects of Meal Frequency on Metabolic Profiles and Substrate Partitioning in Lean Healthy Males. PLoS ONE, 2102; 7 (6): e38632. Available online:

Anthony Colpo is an independent researcher, physical conditioning specialist, and author of The Fat Loss Bible and The Great Cholesterol Con. For more information, visit or

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