Macronutrients, Metabolism & Calories

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March 1, 2017
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March 1, 2017
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There is a lot of detailed information about macronutrients and calories available through easily accessible sources, however for the purpose of this guide, we are going to provide you with simple explanations that are easy enough to help you to build your own meals and to meet your fat loss goals.

Fundamentally, our metabolism refers to physical and chemical processes that occur in the body that enable the body to function normally in order to stay alive, such as breathing, blood circulation and nerve function. To carry out these processes, our body converts the food we eat into energy. Our digestive system breaks down food into fuel which is then used by the body to carry out normal bodily functions or stored in the body’s tissues. One of the key considerations that influences our metabolism is the thermic effect of food. The thermic effect of food simply means that it costs the body in energy (ie calories) to digest, absorb, and store the nutrients in the food you’ve eaten. As a result of the thermic effect of food therefore, by consuming calories you actually increase the rate at which your body burns calories (i.e. increases your metabolic rate) and can account for as much as 5 to 10 % of the energy content of the food ingested. To demonstrate the thermic effect of food, for example, if you eat a 400 calorie meal, you can reasonably expect somewhere between 20 to 40 calories (5 – 10%) to be burned by the body in the process of actually digesting, absorbing, and storing the nutrients from the meal.

There are a number of factors that can influence the degree of the thermic effect of food, including variables that you can influence, such as meal size, meal frequency, the pattern of food intake and meal composition. Factors that influence the thermic effect of food that you can’t control however may include your age, gender, individual hormone levels, and genetics. In terms of meal size, the more calories there are in a meal, the greater the thermic effect of food will be as a result of consuming that meal (assuming that the relative proportions of protein, fat, and carbohydrates remain the same in each meal). On the basis that the thermic effect of food is influenced by the digestion, absorption, and storage of consumed nutrients it seems reasonable that the more nutrients you consume, the more energy your body will need to expend to process those nutrients.

The influence of meal frequency and the thermic effect may be of less importance when it comes to fat loss. Generally the thermic effect of food is greater when a set amount of calories are consumed as one single meal, rather than broken up into many smaller meals eaten over an extended period throughout the day. For example, a 750 calorie meal that takes 10 minutes to eat would result in a higher thermic effect of food than the same 750 calorie meal eaten in six equal portions of 125 calories that take 5 minutes to eat at regular time intervals. Similarly an irregular meal pattern (i.e. 3 meals on one day, 8 meals the next day, 2 meals the next day) may induce a lower thermic effect of food than a regular meal pattern (i.e. a consistent 6 meals per day) that has the same total amount of calories.

The thermic effect of food will also vary depending on the relative proportions of the macronutrients (i.e. fat, carbohydrates, and protein) that make up the meal. Protein is the macronutrient that induces the largest thermic effect of food response. Approximately 25% of the calories in protein will be burned after consumption due to the thermic effect of food while for fat and carbohydrates only about 5% of the calories consumed are expended due to the thermic effect of food. So, for example, if you consume 300 calories of protein you may burn 75 calories (or 25%) through the thermic effect of food. Alternatively if you consume 300 calories of fat or carbohydrates, only about 15 calories (or 5%) will be burned as a result of the thermic effect of food.