Eating 6 meals a day is commonly prescribed to lose fat. Consuming fewer, larger meals will supposedly make you fat and it’s better to have a ‘grazing’ eating pattern with more, smaller meals. The idea behind this is that each meal increases your metabolic rate, so having more meals increases your total daily energy expenditure. If this increases your energy expenditure above your energy intake, you’ll be in negative energy balance and your body will be forced to burn some of its own energy, normally from your body fat stores.
It is true that each meal increases your metabolic rate. This is called the thermic effect of food (TEF), or dietary induced thermogenesis (DIT) and sometimes specific dynamic action (SDA). They’re all the same thing: an increase in energy expenditure resulting from the metabolism of your meal. It takes energy to digest, absorb break down and utilize the nutrients from your food.
However, the thermic effect of food is proportional to the energy intake from your meal.
All the way back in 1982, researchers compared the effect of meal frequency on energy expenditure. Participants were fed 2 or 6 meals with the same total macronutrient composition and energy content in a whole body calorimeter, which is essentially a tightly controlled room that measures all the carbon dioxide produced by the participant and their oxygen consumption. This allows us to calculate precisely their total energy expenditure. The 2 meals resulted in 2 large spikes of energy expenditure compared to 6 smaller spikes in metabolic rate for the 6 meal group. Importantly, total energy expenditure, measured as the area under the curve, was the same in both groups.
All subsequent research has unanimously supported the finding that your meal frequency in itself does not impact your metabolic rate: see the literature overview from our online PT Course below. How many meals you have in your diet does not affect your energy expenditure.
|Study||Population and protocol||Meals per day||Findings|
|Taylor and Garrow (2001)||Overweight or obese females (26) completing a diet in a metabolic unit||6 vs. 4 vs. 2||No overall energy expenditure and NEAT between groups.|
|Kobayashi et al. (2014)||Healthy males (8) completing a diet in a respiratory chamber||3 vs. 2||No difference in 24h energy expenditure, macronutrient oxidation, or thermic effect of food.|
|Iwao et al. (1996)||Well-trained boxers (12) completing a diet in free-living conditions while undergoing boxing training||6 vs. 2||No significant differences in energy expenditure.|
|Smeets and Westerterp-Plantenga (2008)||Healthy females (14) completing a diet in a respiratory chamber||3 vs. 2||No significant effects on 24 h energy expenditure, diet-induced thermogenesis, activity-induced energy expenditure and sleeping metabolic rate.|
|Verboeket van de Venne et al. (1993)||Healthy males (10) completing a diet in both free-living conditions and in a respiratory chamber||6 vs. 2||No significant difference between groups 24 h energy expenditure, daily metabolic rate, basal metabolic rate, or physical activity patterns.|
|Dallosso et al. (1982)||Healthy males (8) completing a diet in a whole-body calorimeter room||6 vs. 2||24h energy expenditure was not significantly different between groups.|
|Munsters and Saris (2012)||Healthy males (12) completing a diet in a respiration chamber||14 (hourly) vs. 3||Total energy expenditure, carbohydrate and fat oxidation, and free fatty acid concentrations were not significantly different between groups.|
In case you’re worried about ‘going into starvation mode’, rest assured your body is easily capable of fasting for prolonged periods in a day. In fact, fasting for over a whole day first increases your energy expenditure for a few days, as it triggers the release of catecholamines like noradrenaline, presumably with the evolutionary purpose of stimulating you to find food. Only after several days of fasting does your metabolic rate downregulate.
You don’t have to eat every few hours. Your metabolism is perfectly capable of handling prolonged fasting periods and your meal frequency does not impact your energy expenditure, given the same energy intake. So you can let other considerations, like your daily schedule and your workout time, guide how many meals you consume per day.