There are some factors that affect metabolism that we can’t change, such as gender, though we can maximize other elements associated with our metabolic rate and look to achieve our ultimate body composition.
1. Basal Metabolic Rate:
Our basal metabolic rate or the amount of energy we need to carry out basic bodily functions - from pumping materials between cells to maintaining our circulation and vital organs as well as keeping us at just the right temperature. Our brain and liver alone account for half of our energy use at rest. It can be affected by amongst other things:-
Body size – the heavier we are the more energy we need to function – there is simply more body to look after!
Muscle Mass – muscle requires more energy to function so the more muscle we have the greater our BMR is
Gender – generally men burn more energy just because they tend to have a greater body size to look after and may have a greater muscle mass
Age – as we age we may see a decline in muscle mass in which case the amount of energy required to maintain this reduced amount also reduces
Environmental temperature – if temperature is very low or very high, our body has to work harder to maintain its normal body temperature, which increases the BMR
Infection or illness – BMR increases because our body has to work harder to build new tissues and to create an immune response
2. Thermic Effect of Food (TEF):
Our metabolic rate rises after a meal as we require energy to chew, digest and metabolise the food we have eaten. Contributing about 10% of our energy expenditure the rise occurs soon after we start eating, and peaks 2 to 3 hours later. Different macronutrients have different thermic effects. It’s no surprise that protein has the highest thermic effect, followed by carbohydrates and then fats. We only have to compare how long it takes to chew and eat a piece of steak compared to some butter to begin to understand how much more energy the body will use to then breakdown the steak and process the protein into amino acids for our body to put to use. As well as protein-rich foods we will also use more energy chewing and digesting sources of fibre and wholefoods.
Therefore, a diet rich in protein, fibre and wholefoods can increase our metabolic rate as well as other improved health outcomes.
3. Physical Activity:
It’s certainly not new news to find that activity uses energy and therefore increases our metabolic rate. Something to bear in mind though is the long-term effects activity may have on our BMR. The more muscle we have the more energy it takes to maintain this muscle which therefore increases our BMR.
So, to conclude we can now understand the urban myth that we may not have a healthy body composition because we have a slow metabolism. Unless we have an underactive thyroid, generally that's not the case. There are though elements of our diet and lifestyle that we can adapt to increase our metabolism such as being more active, increasing our muscle mass and having a diet rich in protein, fibre and wholefoods.
If you would like to know if your thyroid and its hormones are in tip-top condition, wish to find out your personal BMR or are looking to change your Body Composition please come and see me at Bridgford & Bingham Nutrition.
Happy eating,
Nina Thomas
Registered Nutritionist & Food Scientist
07958 765337