Metabolic Myths

Metabolic Myths


We all have that enviable friend who’s living in crop tops despite eating like a trash can, whilst we’re slightly soft around the edges even with the consistent effort to live like a rabbit. Often our metabolism takes the credit, so can you speed it up or slow it down? We investigated the facts.


What is metabolism?

‘The chemical processes that occur within a living organism in order to maintain life’ – aka how many calories you burn by existing. This is known as your basal / resting metabolic rate (BMR).


Is the speed of your BMR genetic?

Like most things in life – it’s a mixed bag. If your genes give you a propensity to be more muscular (for example male BMR vs female BMR) then your metabolic rate will likely be higher, as these muscles are consuming more energy. However you can also build muscle mass through exercise and lifestyle factors.


Are Hormones involved?

Yes. The main ones include insulin, glucagon, ghrelin (hunger hormone), cortisol (stress hormone) and thyroid hormones. These all impact the body’s ability to burn fat, for example if you have an overactive thyroid you will burn more fat whereas an underactive thyroid can lead to weight gain. However this would be a pathological cause of a slow metabolism and is not normal.


Do lifestyle factors affect metabolism?

Yes – you can increase your metabolism by exercising and building muscle mass as this will consume calories at a faster rate, even when at rest. Conversely, living an inactive lifestyle will slow your metabolism. You should also try and get enough iodine in your diet from sources such as cranberries, cheese, eggs, seaweed and yoghurt.


Can supplements help boost your metabolism?

No. The studies used to support the claims of many fad diet pills are often tested on animals using extremely high doses and should not be consumed in this way. Many such tablets either have very high doses of caffeine which can make you uncomfortably anxious and jittery, or laxatives which temporarily make you lose water weight and offer no long term positives.


Does metabolism slow with age?

Yes as you lose muscle mass as you age. You also undergo hormonal shifts such as those related to the menopause.


Can crash diets affect metabolism?

Yes, studies have shown that rapid weight loss can slow your metabolism, leading to future weight gain. It’s not about how fast you can lose it but how long you can keep the weight off – sustainable changes.


Does breakfast really fire up your metabolism for the day?

The research currently shows that there’s little difference in the metabolic rate between those that consume bfast and those that do not. Therefore it comes down to personal preference – if you feel you need a meal to get you out of bed and prevent mid morning snack attacks then it’s clearly the best option for you.


Does staying hydrated boost metabolism?

Yes – water is a vital part of normal cellular functions so being dehydrated can slow these processes down. A recent study by the university of Utah found that when people experience 3% dehydration, their metabolism slows by around 2%.


What’s the best exercise for boosting metabolism?

Anything that builds lean muscle – this can include HIIT and strength training which raise EPOC (excess post-exercise oxygen consumption) from the physiological stress on the body. This works better than low intensity exercises such as walking, although these are still excellent for cardiovascular health.


Is it better to work out on an empty tank?

Some studies have found that exercising in a fasted state can burn up to 20% more calories compared to exercising after eating. This is because once you eat, insulin (which regulates the breakdown of fat) increases in our body. According to some research, higher insulin levels have been shown to suppress fat metabolism by up to 22%. However, another study has suggested eating carbs before working out increases the post-exercise ‘after-burn’ effect more than the fasted state, meaning you’ll burn more calories throughout the day, not just during your sweat session. So again, it’s down to personal preference!


Screen Shot 2018-06-11 at 17.31.10