The metabolic rate can be described as the speed at which our bodies burn the fuel that we eat to produce the energy we need for everyday life. It is a measure of energy output over a period of time. Metabolism may differ by as much as 25% between one person and the next, though much of this may be within our control and is linked to lifestyle factors as much as it is genetics. Provided an individual has no metabolic disorders such as hypothyroidism, metabolism is set by the amount of lean tissue that is present in their body. Muscle is the most metabolically active tissue in our bodies, though the energy used by the digestive and nervous systems is significant.

Metabolic rate is controlled by many varied factors, and is a complex control process. Age, gender, weight, fitness levels, activity levels, food consumption and type, along with genetics all play their part in determining the rate at which our metabolism works. There are also other factors at work such as hormones & the central nervous system, including conditions such as stress and depression.

Can I raise my metabolism?

Yes you can, and it is well within our power to impact on our metabolic rate. Firstly we have to understand the metabolism of food and its conversion to energy, and how our bodies utilise energy that we have made from fuel – food.

How is our energy spent?

In terms of the energy that we burn there are three primary requirements that impact our overall metabolic rate. The proportions are split roughly as follows:

1. BMR – Basal Metabolic Rate

At rest the body requires energy for the heart to beat, circulation and respiration to continue, as well as for body heat, digestion and other bodily functions required for survival. This is your BMR and it accounts for around 60% of energy requirements.

2. Activity levels

A person with average activity will use up around 30% of energy in daily routines. This figure can increase to 60% for a very active person, and can be as low as 15% of total energy output for sedentary people.

3. Dietary Induced Thermogenesis (DIT), and Adaptive Thermic Response (ATR)

These are not considered significant in terms of energy balance and are responsible for less than 10% of daily expenditure. They relate to the energy that our bodies require to process the food that we eat (DIT), and our natural response to changing climatic conditions (ATR).

When we eat

Always start the day with a good breakfast because this will start the metabolism working. Also skipping breakfast usually leads to eating more calories throughout the day, and is one of the first signs of disordered eating that correlates with overweight and obesity. It is worth noting that eating large meals late at night is likely to disrupt sleep, which in turn may lead to fatigue and depleted energy levels thus perpetrating a downturn in physical activity, and possible weight gain.

Can I take a supplement to boost my metabolism?

No. There are many supplements on the market which claim to speed up metabolism, however, despite some claiming their product is backed by scientific evidence, their use can often be dangerous, and using them for long-term weight loss is not appropriate. Most work on the principle of increasing lean tissue mass, which can only be safely done by exercise and regular activity.

What about drugs?

You will not be surprised to hear that our advice is to avoid weight loss drugs like you would a double cheeseburger and chips with a large chocolate sundae fudge on top! The most prescribed weight loss drug in the UK is Orlistat. This intriguing drug binds with your pancreatic lipase (your fat digesting enzyme) so that much of the fat that you eat simply passes through your system. Sounds great doesn’t it? Well aside from the vitamin deficiency that may follow due to the low uptake of fat-soluble vitamins, there are other unpleasant side effects: frequent, urgent and oily bowel movements, foul smelling flatulence, and leakage of oily residue from the rectum. Orlistat is usually only available for a maximum of 12 months, and very few people using Orlistat go on to maintain their weight loss longterm when the drug is withdrawn.

Thanks doc but no thanks!