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How to speed up your metabolism naturally


Page last updated: 17th December 2021

Metabolism is one of those magic buzzwords which gets thrown around a lot. The average gym-goer is well aware that a fast metabolism is supposed to be the secret to effortless weight management, but with dozens of products on the market boasting the ability to boost your metabolism and turn you into a fat-burning machine, as well as numerous exercise plans and lifestyle tips, it can be hard to figure out where the truth ends and the myths begin. 

So, what does metabolism actually mean? And can you really change how fast it works?

What is metabolism? 

Simply put, metabolism refers to the process your body goes through when it changes the calories from food into energy. However, it’s actually split into two different activities: 

  • Catabolism (destructive metabolism) - the process by which cells break down molecules from mainly carbs and fats to gain energy. This is great for fuelling anabolism and generally powering your body.
  • Anabolism (constructive metabolism) - the process by which cells build up body tissues and energy stores.

So you’ll metabolise the foods you consume and use them to fuel, fix, grow, energise and maintain your body. 

Why would I want to speed up my metabolism?

Metabolism is generally discussed in relation to weight control - if your body can’t, or doesn’t need to metabolise all of the calories you’re consuming, then you may be likely to gain weight. Likewise, if you’re burning more calories than you can metabolise, then you’ll be likely to lose weight.

Your Basal Metabolic Rate (BMR) is how many calories your body burns just by existing - pumping your blood, breathing and so on. It makes up the bulk of the energy you burn each day. You can then increase the number of calories your body can metabolise by using more energy, through movement and exercise. If the amount of calories you consume matches the amount you burn, your weight will stay stable. We explain a lot more about BMR and how to work out how many calories you need here

Not all metabolisms are made equal - BMR can be affected by factors such as genetics, health, body composition, activity levels and more. You may simply be born with a very fast or slow metabolism, or health issues may have slowed yours down, meaning you can’t burn the energy you’re consuming from food as fast as other people. 

Also, our metabolisms naturally slow down as we age, so even if you once found it much easier to lose weight without having to focus too closely on your diet and fitness, you will likely find it much more challenging as you get older. 

How to speed up metabolism

In general, increasing your exercise is the best way to increase your metabolism but if you’re interested in boosting it even further, then you could try the following:

  1. Focus on short, intense exercise, like HIIT

    A series of studies have, in recent years, given credibility to the old fitness guru claim that intense workouts can help to boost your metabolism. One 2011 study [1] found a significant increase in metabolic rate following an intense 45-minute bout of cycling. What’s more, the metabolism of the test subjects remained elevated for 14 hours after the end of the exercise.

    When it comes to speeding up your metabolism, try focusing on completing short but intense workouts like HIIT that will challenge you and get your heart rate high. 

    This guide explains more about HIIT, along with some fantastic example workouts you can try.

  2. Build muscle

    You’ll see it written time and time again that muscle burns more calories than fat, meaning replacing fat stores with more muscles should help you naturally metabolise quicker. Studies have shown this to be true, however the difference could be fairly small - a study from 2003 highlighted that 4.5lbs of muscle mass would increase the resting metabolic rate by about 50 kilocalories per day. 

    This shouldn’t be the sole focus with building muscle though - instead, it’s important to consider the process of working and strengthening your muscles. Weight training has now been proven to burn more calories than was previously thought and resistance training can elevate your metabolism for up to 48 hours after your workout

    Learn more about resistance training and its benefits here.

  3. Eat plenty of protein

    Boost your metabolism by eating protein. Diet-Induced Thermogenesis (DIT) is a term used to describe how much energy is spent dealing with food. Protein has the highest DIT value, meaning your metabolic response will be higher right after a protein-rich meal.

    Check out the High Protein Recipes section of our blog for inspiration for your next protein-packed meal.

  4. Drink green tea

    This is one of those claims which is often met with scepticism by certain elements of the health community. At least one study from 1999[2] did find, however, that a green tea extract significantly boosted the 24-hour energy expenditure of test subjects while also improving fat oxidation.

    Other studies have come to similar conclusions.

    A 2014 meta-analysis[3] found that green tea did have a positive (though minor) impact in promoting fat loss, with the effects being stronger for certain ethnicities than others and also for subjects who consumed different levels of caffeine on a daily basis.

    If you're looking to boost your metabolism naturally, try swapping your usual cup of coffee with green tea to get your caffeine hit.

  5. Get the sleep you need

    While there doesn’t seem to be much evidence to suggest that getting “a lot” of sleep boosts your metabolism any more than getting “enough” sleep, the science is clear on one fact: being sleep deprived ruins your metabolism at various levels and promotes fat gain.

    One 2007 study[4] found that sleep deprivation not only had a negative effect on appetite (causing subjects to over-eat) but that it also lowered overall energy expenditure in the body (meaning that the excess calories were significantly more likely to be stored away as fat) while also having a negative effect on insulin resistance.

    Not sleeping enough is well known to be one of the worst things an individual can do for their overall health. A terrible metabolism is clearly one part of that. Make sure to get enough rest, and sleep by setting an alarm for when to go to bed.

    For more tips on getting restful sleep, check our blog on all about how to get better sleep.

Metabolism-boosting myths

There’s a lot of discussion about whether the way you eat can affect your metabolism. Here, we’ve busted a couple of popular myths that we regularly hear… 


This is one of the most persistent myths surrounding metabolism, even though it’s also one of the most clearly debunked and refuted. A 1993 study from the University of Limburg[5] found that meal frequency had no statistically significant effect on metabolic rate and overall energy expenditure.

This research has since been backed up by numerous other studies.

The bottom line is that you need to be watching the total number of calories you consume in a day. Whether you eat 3 or 6 meals is unlikely to have an impact on anything other than how full you feel at any given time and how likely you’ll be to overeat or not.


The idea that eating before bed causes a metabolic crash has been doing the rounds for some time.

However, one large 2015 scientific survey[6] of the available data suggests that things aren’t quite so straightforward.

Large, calorie-dense meals just before bed, combined with irregular sleep patterns, do seem to have a potential negative effect in promoting fat gain. Likewise, eating before bed does appear to present certain specific problems for obese individuals.

These results are not consistent, however. Obese individuals seem able to completely avoid the negative side-effects of eating just before bed by exercising regularly – and those negative effects don’t seem to apply to fit individuals at all.

Also, while eating large meals just before bed might not be ideal, eating a small nutrient and protein-rich meal seems to not only improve overnight muscle growth but also leads to a faster metabolism the next morning.


The PureGym blog is brimming with ideas for exercises and workouts you can do to build muscle and burn calories. You can also check out our diet and nutrition section for healthy food ideas as well. If you’re ready to sign up to the gym and need a little help getting started, then our fitness classes and Personal Trainers can help you on your fitness journey. 


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