Your body burns more calories after a meal with fish oil

Fish oil supplementation boosts energy expenditure after a meal, so it makes weight loss or maintenance of a healthy weight a tiny bit easier. Canadian nutritionists at the University of Guelph discovered this from an experiment they did on six men whose glucose and insulin balance was out of whack.

N-3 fatty acids
The polyunsaturated n-3 fatty acids in fish improve body composition. Studies show that they increase muscle mass and also help muscle mass to react better to strength training. They also induce the body to burn more energy. Studies also show that people who consume large amounts of fish fatty acids are less fat than people who consume low amounts of the substance.

The Canadians were most interested in finding out about the fat-decomposition effects of fish oil. They were curious to know whether functional foods, to which manufacturers had added extra fish fatty acids, would help people with metabolic syndrome – the combination of overweight and diabetes – to achieve a healthy weight.

The researchers got their subjects to eat food containing high concentrations of n-3 fatty acids for a period of 14 days. A list of the products is shown below. As a result of the diet, the intake of EPA and DHA rose from 0.4 to 2.9 g per day.


The 14 days were too short to reduce bodyweight or fat mass, and the amount of fat that the men burned while resting didn’t increase either. What did change was the postprandial thermic effect of food [postprandial TEF]: the increase in energy expenditure occurred every time after a meal. At the end of the 14 days it had increased by 51.3 percent.


The researchers measured the TEF after a hot meal containing 920 calories. The meal contained 1.4 g DHA+EPA.

The thermic effect starts to decline a few hours after a meal. From this you can conclude that fish oil supplementation for dieters works better if they spread their capsule intake over the different meals.

N-3 polyunsaturated fatty acids increase thermic effect of food in men with metabolic syndrome.


Effects on energy metabolism of a test meal and a two-week dietary intervention were observed in men with metabolic syndrome (MetS). Both the meal and the intervention included foods containing fish-derived n-3 polyunsaturated fats (PUFA).

Six men with MetS (46.7 ± 12.1 years, 37.2 ± 5.6 kg/m(2), mean ± standard deviation) completed two test days, separated by a 14-day dietary intervention during which they consumed at least 2.0 g per day of n-3 PUFA from supplied foods. Pre- and post-intervention measurements included body composition, resting metabolic rate (RMR), and the thermic effect of food (TEF) measured for six hours after ingestion of a test meal consisting of 1.43 g of fish-derived n-3 PUFA.

Intakes of n-3 PUFA increased over the 14-day intervention, from 0.43 g per day ± 0.48 to 2.92 g per day ± 1.97 (p=0.013), while no changes were observed in total energy intakes, weight, body composition, or RMR (all p>0.05). The TEF increased by 51.3% (p=0.036), and the non-protein respiratory quotient decreased by 36.0% (p=0.700).

Subjects increased their intake of fish-derived n-3 PUFA in an isocaloric manner while maintaining body weight and composition, and increased the TEF. More studies with larger sample sizes and longer intervention periods are required to confirm the use of fish-derived n-3 PUFA as a therapeutic dietary strategy for people with MetS.

PMID: 22146121 [PubMed – indexed for MEDLINE]