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Can I speed up my metabolism?

“Metabolism” is a word we hear a lot in connection with our weight and many people have been led to believe that they have a slow metabolism, which prevents them from losing weight.

When we speak about our metabolism, what we’re really talking about is our “resting metabolic rate”. This is the baseline amount of energy our body needs to carry out all of the chemical processes in all of our cells – for instance, digestion, breathing and transporting substances in and out of cells.

Your resting metabolic rate accounts for anything between 40 and 70 per cent of your total energy expenditure. It’s determined by factors such as your age, height and activity level. But while it differs from person to person, few of us have a particularly fast or slow resting metabolic rate, and its unlikely to be a big reason why you’re fat or thin.

However, speeding up our resting metabolic rate can still be useful. Over time, using a few more calories every day could help us to control our weight.

So is there anything you can do ‘boost’ your metabolism?

The experiment

We took 28 volunteers and split them into three groups, with each doing one of three interventions over eight weeks.

  • The first group drank one litre of water every day that was chilled to fridge temperature (5 degrees C). The idea is that drinking cold water means your body has to use energy to warm it up to body temperature (a process known as thermogenesis).
  • Our second group drank decaffeinated green tea four times a day. This contains natural chemicals called catechin polyphenols that are claimed to raise our metabolic rate and tell our bodies to burn more fat.
  • Group three did sets of exercises using a resistance band, totaling an hour of exercise a week. The idea here was to build up muscle and lose some fat. Muscle tissue requires more energy to maintain it than fat tissue does, so this should lead to a rise in the resting metabolic rate.

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Results

  • Cold Water – Although there were some individual changes in weight in this group, there was no overall change in the group’s average resting metabolic rate. It’s likely that if the proposed mechanism for water worked, the effect was very slight and undetectable after eight weeks. Other studies that have looked at water have also proved inconclusive.
  • Green tea – There were also individual changes in weight within this group, but no change in their overall resting metabolic rate. Again, if the proposed mechanism worked, its effect was so slight as to have a negligible effect. Other studies that have looked into green tea in this regard have also struggled to find an effect.
  • Exercise – The DEXA scan showed that seven out of our nine volunteers had added lean muscle mass to their body composition. Over a longer period of time, we would expect to see a change in their resting metabolic rate if their progress continued.

What this means

Our experiment showed that any ‘quick fix’ that claims to be able to boost your metabolism and help you lose weight is unlikely to work.

That there was no change in our first two groups indicates that there are few things you can do to raise your resting metabolic rate effortlessly, and this is backed up by wider scientific research.

However, the progress made by our exercise group in just 8 weeks was promising, and other research in this field also confirms that one of the best ways to try and boost your resting metabolic rate is to build more muscle, as your body will need to burn more calories to maintain it.