Myths busted: Can certain foods speed up your metabolism?
Does eating chilli really help you lose weight? Dr Janet Franklin tells us if what (and how) you eat can really affect your metabolism.
Q: Is it true that some foods can ramp up your metabolism?
A: All foods, to some extent, will increase metabolism. This is called the thermic effect of food and it accounts for roughly 5–10% of our total daily energy expenditure (210kJ–1050kJ), depending on what and how much you eat, your size, gender and age. It’s also been shown that some macronutrients – like proteins and Medium Chain Triglycerols (MCT) – and foods like oolong tea, green tea, caffeine and chillies (capsaicin) might increase this effect more than others.
Q: How much of an effect do they have?
A: Research has shown that the impact of the thermic effect of food on actual energy expenditure is generally small. Some examples of this include:
Eating 100g protein – in comparison to carbohydrate and fat – burns an extra 42–63kJ.
Drinking five cups of oolong tea, green tea or a caffeinated beverage per day increased total energy expenditure by 98.8kJ, 48.8kJ and 38.3kJ, respectively.
Adding 30mg capsaicin (10g chilli) to a meal increases energy expenditure by 20–60kJ per meal (depending on the chilli’s heat).
Q: How does food compare with exercise for speeding up metabolism?
These foods are yet to be proven to have a long-term impact on weight. Furthermore, the large doses that are often required to provoke the increase in energy expenditure may lead to gut disturbances, a rise in LDL cholesterol and/or anxiety.
By far the greatest contributor news to daily energy expenditure is our resting metabolic rate (RMR), which contributes 60–70% of our total daily energy expenditure. The factors that affect RMR include age, gender and muscle mass – muscle mass being the only factor that we can change.
Physical activity is the one factor that impacts our daily energy expenditure the most. It accounts for 5–30% (380kJ– 3150kJ) of your total energy expenditure, plus it has the potential to increase muscle mass, thus impacting on your RMR.
Although it’s unlikely that adding foods to increase energy expenditure will lead to large amounts of weight loss, it may help with weight maintenance, maintaining RMR while following a low-kJ diet and off-set small energy intake increases.
The bottom line
Foods that increase energy expenditure may make small differences to your daily energy output. However, changing your total energy intake and activity patterns are proven to have significant impact on weight.
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