Speeding up your metabolism: what changes and what doesn't

Can you speed up your metabolism? Yes, but less than internet promises suggest. The part of your basal metabolic rate that depends on genetics, age and height doesn't change with anything you do. What you can change is relatively modest, and the most solid path is building muscle with strength training and staying physically active through the week. None of it is dramatic. It is, however, real.

That's the honest answer. Everything else that tends to appear in headlines — teas that "melt fat", foods that "fire up" the engine, miracle supplements — deserves a more sceptical explanation than it usually gets.

What is metabolism, really, and why does it seem slow?

Basal metabolic rate is the component that the evidence describes as difficult to change significantly. Reference medical institutions are clear on this: basal metabolic rate doesn't change much by willpower, because it depends on factors you don't choose.

Genetics, age and height all count. No diet alters them. What can raise your basal rate healthily is muscle mass, because muscle tissue demands a lot of energy to maintain. Regular, progressive resistance training is the realistic route.

On the other hand, some things lower basal metabolic rate. Skipping meals, prolonged fasting or eating too little make the body slow down to protect itself. Age counts too, especially through loss of muscle mass. Menopause, for the same reason, and hypothyroidism, through low thyroid hormone levels. If you recognise a pattern here that isn't explained by food or routine, it's worth talking to a healthcare professional.

So what makes metabolism slow down?

The most common causes are nothing mysterious. Eating little consistently, whether through restrictive diets or skipped meals, is one: the body responds by lowering expenditure. Losing muscle over time — through lack of strength training or ageing — is another. Poor sleep weighs in too: adults need seven to nine hours a night, and sleep deprivation is associated with weight gain and greater hunger, as well as making less healthy food and drink choices more likely.

There's also a hormonal component. The thyroid regulates much of the metabolic rate, and low thyroid hormone levels slow it down. This isn't a matter of discipline. It's physiology.

And there are clinical situations that speed up metabolism harmfully. A very fast metabolism isn't necessarily good: hyperthyroidism or the use of certain stimulants can speed it up, but can also harm health. If the idea of "speeding up" always sounds positive to you, this is the exception worth keeping in mind.

What you can change this week

Start with what has the most support. Regular strength training is the best-founded measure for increasing muscle mass and, through that, resting energy expenditure. You don't need hours in the gym. You need consistency over months, not one heroic week.

Then sleep. Seven to nine hours a night, with regular times, isn't decorative advice: sleep deprivation is associated with more hunger and worse food choices. And finally, food. A recent review suggests that a higher protein intake increases thermogenesis — the heat the body produces digesting food — and satiety compared with diets lower in protein, although results on weight and fat loss haven't been consistent and longer studies are needed.

This means protein probably helps with satiety and digestive expenditure. It doesn't mean it transforms your metabolism. Treat it as one piece among several, not the main lever.

Increasing physical activity in general — walking more, taking stairs, moving through the day — counts too. A Harvard review on the subject concluded that it's generally quite difficult to change metabolic rate significantly, and that the most reliable first step is improving the type of foods you eat and increasing physical activity. Less exciting than a bottle of capsules. More true.

What tends not to work

Eating very little to "speed up" can backfire. Aggressive calorie restriction lowers basal metabolic rate. The body protects itself, and you end up slower, not faster.

There's also no solid evidence that any food or drink can speed up metabolism relevantly. The idea that certain teas, spices or juices "activate" metabolism is repeated endlessly, but the pack doesn't support that idea. It doesn't support a strategy.

High-intensity exercise is often presented as a shortcut. It may have its place, but it's demanding and doesn't replace strength training or consistency. And it's not for everyone, especially if you're returning to activity or have health limitations.

Above all, distrust any promise of quick, visible results. Metabolism doesn't have a button. It has small levers, which move slowly.

Where supplements fit — and where they don't

Here we need to be direct: no supplement is the solution for speeding up metabolism. Some of the ingredients that appear in products in this category — apple cider vinegar, iodine, folic acid, vitamins B6 and B12 — have established nutritional roles, but there's no evidence supporting the idea that they significantly speed up metabolism. Iodine is a nutrient with an established nutritional role, but there's no evidence in the pack supporting the idea that taking extra iodine speeds up metabolism.

Appetite Control Gummies are a food supplement for adults: two gummies a day. Per serving they contain apple cider vinegar, vitamins B6, B12, folic acid, iodine and pomegranate and beetroot juice powders. Do not exceed the recommended daily dose. Like any supplement, it doesn't replace a varied and balanced diet or a healthy lifestyle. Contains polyols; excessive consumption may have laxative effects. In case of pregnancy, breastfeeding, illness or use of medication, consult a healthcare professional before consuming. And keep out of reach of young children.

Note what this product doesn't promise: it isn't a metabolic accelerator and shouldn't be treated as one. If your goal is to increase energy expenditure, strength training and sleep remain what matters.

When this stops being normal

There's a difference between a metabolism that seems slow and a health problem. Extreme tiredness, feeling cold often, weight gain and low mood are common symptoms of an underactive thyroid. These symptoms are frequent and can have other causes. If you suspect this might be you, see your GP: diagnosis is made with blood tests.

The opposite deserves attention too. Having a very fast metabolism isn't always a good sign: hyperthyroidism or taking certain stimulants can speed up metabolism, but can also be harmful to health. Talk to a professional.

Outside these cases, what you feel may be related to habits such as routine, sleep, food and lack of strength training. It's a set of habits that can be adjusted.

How long until you notice a difference

Don't expect changes in days. Building muscle is a healthy way to increase resting energy expenditure, because muscle tissue demands a lot of energy to maintain. Give yourself at least two to three months of consistency before judging whether it's working. If after that time there's no change in your weight, energy or body composition, it's worth reviewing your approach with a professional — and not buying another bottle.

What you can do today: put two strength sessions in this week's diary, set a realistic bedtime and make sure you have enough protein at each main meal. Simple, unglamorous, and probably more effective than anything promising to speed up your metabolism in a weekend.