What You Need To Know About Your Metabolism

We all know someone who seems to be able to eat what they like and stay slim. But how much of that comes down to a fast metabolism? We asked some nutrition experts to share their insights. From the impact of exercise to why it could be worth taking probiotics, here’s what they had to say…
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First, what exactly is your metabolism?

In a nutshell, it’s what’s going on inside your body when you’re at rest. As Kim Plaza, technical advisor at Bio-Kult explains, the body requires a basic amount of energy to carry out processes such as breathing, digestion and cell repair, and this energy comes from food. “The minimum amount of energy your body needs to carry out its job is the basal metabolic rate (BMR). This is how many calories you’d burn to just stay alive even if you sat on the sofa all day and didn’t do anything. BMR accounts for around 60-75% of your daily calorie expenditure and having a slower rate could have a substantial effect on whether you maintain, gain or lose weight.” 

Is it useful to know your BMR?

Yes, because it can give you an idea of how many calories you should be consuming, adds PT and Bio Synergy nutritionist Daniel Herman. BMR accounts for around 70% of daily energy expenditure (around 10% of energy is burned digesting food and around 20% by physical activity). Official NHS guidance says women should consume around 2,000 calories per day, but the reality is this figure is based on someone who leads a moderately active lifestyle. If you’re an Olympic athlete, you’ll need more, and if you sit at a desk all day and don’t do much exercise, you’ll need less. If you want to work out your BMR, you can find an online calculator – look for those that use the Harris-Benedict equation, which is widely regarded as the most accurate. 

Are you born with either a slow or fast metabolism?

“It’s tricky to say how much of your metabolism is down to your genes,” says David Wiener, training and nutrition specialist at Freeletics. “There are some genetic health problems which can have an effect, such as hypothyroidism (which can lead to a decreased metabolism) and hyperthyroidism (which can lead to an increased metabolism), but it’s more likely down to factors such as age, muscle mass and activity levels. However, some people are born with more muscular body types than others, and these people will naturally have a faster metabolism.” Plus, the notion that the struggle to manage weight is down to slow metabolism is a myth. Research shows that overweight people have faster metabolisms than lighter people because they need more energy to carry out basic functions. 

“The notion that the struggle to manage weight is down to slow metabolism is a myth. In fact, the lighter you are, the slower your metabolism.”

Does metabolism really slow once you reach 30?

Yes, but there’s plenty you can be doing to counteract the decline, says Kim. “Muscle mass naturally decreases with age (you lose around 3-5% of your muscle mass per decade after the age of 30), which means your muscles use less energy and your BMR declines, so you risk being in energy excess if you eat the same amount of food and do the same amount of exercise.” With age, the amount of physical activity people do often declines too, further shifting the balance of energy to excess and risking weight gain. “However, recent studies suggest we may have more control over our metabolism than first thought, and that increasing age may not be an excuse to side-step lifestyle and dietary changes,” she says.

So, what role does exercise play?

If you want to give your metabolism a helping hand, factor in strength training – it will help build lean muscle, which is three times more metabolically active than fat. One study found the average woman in her 30s who trained with weights (or bodyweight) for 30 to 40 minutes, twice a week for four months, will increase her resting metabolism by 100 calories per day. David is also a fan of HIIT when it comes to stoking metabolism. “Countless studies have shown HIIT trumps LISS (low intensity exercise such as walking or slow jogging) in the metabolism game. HIIT and strength training cause more physiological stress to the body, raising something called EPOC (excess post-exercise oxygen consumption), which allows your body to burn calories even when in a rested state. LISS, on the other hand, has been found to have insignificant EPOC effects, meaning there is little or no change to metabolic rate.” Kim is also a fan of weight-bearing exercise, particularly when combined with a protein-rich diet. “One study found that after nine months of resistance training and protein supplementation, individuals increased their BMR by around 5%.”

Do certain foods influence metabolism?

While some studies have shown certain foods, such as green tea and spicy food, can increase metabolism, the increase is very minor and short-lived. “It’s not as simple as ‘eat this to boost your metabolism and lose weight’,” says Daniel. “Plus, when it comes to weight loss, metabolism isn’t the only factor.” Nonetheless, the one food experts agree can have a positive effect on metabolism is protein. “Protein requires more energy to metabolise when compared to both fat and carbs,” Gideon Remfry, wellness director at KX Life and KXU, tells SL. “In fact, studies suggest protein-rich foods can increase your metabolic rate by 15-30%, whereas carbs will raise it by just 5-10% and fat by 3%. Keep your protein intake high by including a good-quality source of protein at each meal, especially breakfast.”

What about hydration?

Research suggests the more hydrated you are, the more efficiently your body works. After all, the body is 60% water, meaning it plays a role in just about every bodily function. “Staying hydrated is recommended for a healthy metabolism,” says Kim. “In fact, evidence suggests drinking water may temporarily speed up your resting metabolism by as much as 30%, and that metabolism can be slowed by even relatively mild levels of dehydration.” Drinking water appears to stimulate thermogenesis – or heat production – in the body, particularly when it’s chilled. The body has to expend energy to warm liquid to body temperature, and the more energy expended, the faster your metabolism.

“An imbalance in gut bacteria could be responsible for a declining BMR, with studies showing a probiotic supplement can help manage weight.”

Can supplements help?

It could be worth taking a probiotic, says Kim. “Research indicates that the composition of your microbiome plays a role in the metabolism. An imbalance in gut bacteria is often seen in overweight individuals and those who make poor food choices. Research suggests that the obese microbiome may harvest more energy (i.e. calories) from the diet, trigger food cravings, manipulate taste receptors and increase total body fat. Your microbiome may also be responsible for fast declines in BMR.” In this light, consider taking a multi-strain probiotic, which could ultimately help rebalance the gut, support healthy digestion and decrease waist circumference, body mass index and fat levels. 

Finally, does eating late at night affect your metabolism?

Only if you’re not eating well, says Daniel. “There isn’t much research that shows eating after 8pm causes weight gain. The reason you may gain weight when eating late in the evening is likely due to mindless snacking and excess calories as opposed to just timing.” If you do have to eat late, make smart choices – meeting your calorie needs won’t cause weight gain, but overeating will.

 

For more information visit Bio-Kult.com, Freeletics.com, KXLife.co.uk and Bio-Synergy.uk

 

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