Now that I’ve got your attention with a clickbait title, it’s time to dispel some myths around foods that boost your metabolism.
Firstly, let me explain the term metabolism. Metabolism is also known as metabolic rate, or the number of calories that we burn during the day. Energy metabolism is a constant process that continues from the day we’re born to the day we die, and we are constantly breaking down fat, carbohydrates and protein to provide us with energy and rebuild cellular structures.
We can break metabolism down into a few key areas. Basal metabolic rate, or BMR, the thermic effect of feeding, or TEF, and exercise activity thermogenesis.
BMR is the number of calories that we burn at rest. If you were to lie and breathe all day and do absolutely nothing else, this is the energy that’s required just to keep you alive. We can’t do a whole lot to influence our BMR as this is mostly determined by our body weight. People with a higher body mass will have a higher BMR than their smaller counterparts, because they have more body tissue to sustain.
Increasing your muscle mass can also increase BMR, however it’s not quite as dramatic as some fitness influencers have probably led you to believe. Each additional pound of muscle burns an additional 6-10 calories per day. Even if you were to gain 10 pounds of muscle, this would only equate to an increase of 60-100 extra calories burnt at rest.
Then we have the thermic effect of feeding. This is the energy that’s required to digest food. Around 10-15% of our daily energy expenditure comes from this thermic effect of feeding, with protein requiring the greatest amount of energy to break down of the three main macronutrients.
I suppose you could argue that food itself is inherently metabolism boosting!
The truth is, there simply are no foods that will meaningfully increase your metabolism. While compounds such as caffeine and capsicum have been touted as magical, metabolism boosting foods, while they may have a small thermogenic effect, the increase in metabolic rate that they provide is unlikely to have any notable effect on body composition.
When it comes to foods that ‘boost metabolism’, there are a lot of flaws within the research. For example, the majority of the research into these areas has been conducted in rats and simply can’t be extrapolated to humans. There’s also the issue of foods and supplements being used within a study design that prescribes a calorie intake that will result in an energy deficit alongside an exercise prescription. This invariably makes it difficult to separate out the impact of the supplement vs the impact of just creating a calorie deficit that is adhered to.
The final component of our metabolism is exercise energy expenditure.
This can be further sub-divided into none exercise activity thermogenesis (NEAT) and exercise activity thermogenesis (EAT), but essentially, this component of metabolism accounts for all of our movement, as movement requires energy. The more we move, the more we increase our energy requirements.
But let’s jump back to the original question. Can we acutely ‘boost’ our metabolism?
To some extent, yes. As I just mentioned, you can increase how much you move during the day, which will make you burn more calories, thus, increasing your metabolism.
But how about food and nutrition?
This is quite a complex question to answer and I could easily go down the rabbit hole of discussing complex human physiology, so I’ll try to keep it as understandable as possible!
Our metabolism is unique to us and different people’s metabolic rates will respond differently to conditions such as an energy deficit or an energy surplus. When some individuals enter an energy surplus, i.e., they start consuming more calories than their body currently burns on a day-to-day basis, they actually don’t gain as much weight as we would expect them to, or any weight at all for that matter, depending on the magnitude of the surplus. This is because their body finds other ways to utilise those additional calories, for example, improving growth and repair, unconsciously moving around more and fidgeting, and generally becoming less economical and more wasteful with energy.
Under the same conditions, other people will gain closer to the expected amount of body weight as their bodily processes just don’t adapt in the same way.
We can also see this adaptation in the other direction, with a calorie deficit causing some individuals to see a massive down regulation in some physiological processes, loss of menstrual cycle in women, loss of sex drive and spontaneous reduction in physical activity as our bodies try to be thrifty and conserve as much energy as possible by burning fewer calories.
So when it comes to specific foods to boost metabolism, no, stop, direct your attention and your energy elsewhere, towards things that will yield much bigger results, like creating a viable nutrition strategy for you and your goals.