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Strength training and metabolism: how lifting weights boost metabolic health

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Getting stronger doesn’t have to be about fat loss but it’s a fact that strength training can significantly improve our metabolic health. By priming the body to use fuel more efficiently, not only can we build muscle but also power and energy – leaving us ready to tackle whatever comes our way with renewed vigour. 

When many people talk about “boosting metabolism,” they focus on dieting and fat loss – but improving metabolic health is about so much more than aesthetic goals. Having an increased or “high” metabolism actually means being able to access energy quickly from food and get rid of waste efficiently. A sluggish metabolism, on the other hand, has the opposite effect and can lead to chronic illness

Like so many other things, strength training can strengthen metabolism – leaving us feeling more energised, more powerful and better rested. So, what exactly is metabolism and how does weight lifting improve it?

Metabolism is “the process by which your body converts the food you consume into energy for immediate use or to be stored for later,” explains the experts at metabolism tracking company, Lumen. When “normal” metabolism gets disrupted, the risk of developing chronic conditions such as type II diabetes, cancer and metabolic syndrome increases. Metabolic health is important.

Plenty of companies say that you can improve your metabolism by drinking certain teas or embarking on wild plans but it’s important to note that these often “work” by speeding up the rate at which food passes through us – having a laxative effect – and raising our heart rate via copious amounts of caffeine. Needless to say, these aren’t healthy or sustainable. To improve your metabolic health, you need to move regularly and eat well, and there is tonnes of evidence to strongly suggest that strength training can help you to move better, feel more powerful and improve your metabolism.

What does a “healthy” metabolism look like?

As with most things in health, a healthy metabolism is more something you can feel rather than see. From a nutritional point of view, someone who is metabolically healthy is able to efficiently switch between using fats or carbs for fuel – meaning that the “key factor in metabolic health is metabolic flexibility,” says Lumen. That means being able to reap the benefits of a bowl of oats while running a half marathon and stay energised at your desk if you skip breakfast in the morning. 

Optimal “metabolic flexibility” can offer lots of benefits, including:

“When we are unable to fuel our body with the required energy source, it works less fluidly or slows down. As we get older, our lean body mass decreases which also impacts our metabolism because we need fewer calories to fuel that depleted muscle mass,” explains Ulrike Kuehl, registered dietitian at Lumen. This means that we need less fuel and Ulrike says that it’s that which slows your metabolism. The lower your need for fuel, the slower your metabolism (which is why crash diets are such a bad idea!).

Bowl of oats
A healthy metabolism can help us to make proper use of the food we eat – without causing any significant hikes or dips in blood sugar levels.

Strength training helps to raise metabolic rate

While a balanced diet of healthy fats, protein and plenty of vegetables can definitely help to keep your metabolism in check, exercise plays an absolutely crucial role in supporting it.

Your resting metabolic rate (RMR) is the number of calories that your body requires to stay alive. Everyone has a different RMR, depending on their muscle percentage and exercise regime. One person’s RMR might be a lot higher than someone else’s, despite them being the same height. That means prescribing a daily intake of 1,250 calories, for example, will leave some people feeling fine and others feeling horrible. Your RMR accounts for up to 75% of your overall energy expenditure if you don’t exercise, but the more you train, the more energy you need to go about your life outside of the gym.

A review of 18 studies found that resistance training was effective at increasing resting metabolic rate, unlike cardio exercise, which had a much smaller impact. It’s worth noting that this is only the case if you incorporate your big, powerhouse muscles and full-body movements into your workouts, because the whole body works harder by engaging a larger amount of muscle. 

Lifting weights produces an “after-burn effect”

The stronger you get, the more energy you end up burning every day when your body is at rest, with research showing that your metabolism stays elevated for up to 38 hours after a strength training workout.

When we lift weights, our muscles need more energy to operate and that energy is only accessible when oxygen helps to break down fat and carbohydrates. During exercise, we breathe faster and our hearts beat harder to pump more oxygen, fat and carbs into our muscles. When we finish the session, that oxygen uptake remains elevated because our muscles still need those fats and carbs to be broken down to help them repair and return to a rested state. That process is known as “excess post-exercise oxygen consumption” (EPOC), or the “after-burn effect”.

If fat burning isn’t your goal, you can rest easy in the knowledge that your body is becoming stronger even after you’ve finished working out. Emma Obayuvana, SWTC trainer, points out that it’s crucial to remember that fat and weight loss have little-to-no correlation to how strong you can feel from lifting weights.

Have a go at the metabolism-boosting, compound move below: push press.

Building muscle boosts metabolism

We all know that lifting weights builds lean muscle, but you may not know that building muscle can increase metabolism. While exercises such as running can help to burn body fat, they may also decrease muscle size – leading to weaker muscles and unintentional weight loss (muscle is more dense than fat). If you don’t fuel effectively, the body can end up eating into its own muscle stores to keep it going over long distances (think: running your first marathon). Evidence shows, however, that strength training not only helps to burn excess body fat but also increases muscle size and strength.

“By strength training, we increase our muscle mass,” explains Emma. Having more muscle has been shown to be one of the factors that may increase metabolism, but as Emma explains, that’s “largely based on an individual’s base metabolic rate and body mass,” and therefore isn’t something we can quantify en masse.

Strength training helps with absorbing nutrients

Metabolism is largely to do with how we use what we eat and the better our system works, the more able we are to absorb all the goodness that’s in our food. Fundamentally, we eat to get certain vitamins and minerals – if we’re not able to absorb them, we become malnourished. Fortunately, Emma confirms, strength training enables “our bodies to absorb macronutrients (such as proteins and fats) more efficiently while increasing the rate at which toxins and waste are removed.”     

Interested in picking up some simple and nutritious recipes? Make sure you check out the rest of our meal ideas in the SWTC library

Image: Getty

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Miranda Larbi

Miranda Larbi is the editor of Strong Women and Strong Women Training Club. A qualified personal trainer and vegan runner, she can usually be found training for the next marathon, seeking out vegan treats or cycling across London on a pond-green Tokyo bike.

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