Short answerYou cannot speed your metabolism up like a dial, but five things genuinely move it: building and keeping muscle with two strength sessions a week, eating enough protein spread across meals, moving more outside exercise, sleeping properly, and avoiding repeated crash diets. Green tea, chilli, six small meals and metabolism boosting supplements do not meaningfully change your total energy expenditure.
Metabolism is not a speed setting you can turn up. It is the total of everything your body spends energy on, and most of that total is fixed by your size, your muscle and your age. What you can change is real but narrower than the internet suggests, and it is worth knowing which levers actually move.
Where your energy actually goes
- Roughly 60 to 70 per cent keeps you alive at rest: organs, brain, breathing, temperature.
- Around 10 per cent is spent digesting and processing food.
- The rest is movement, and most of that is not exercise. It is walking, standing, fidgeting and everything you do outside the gym.
That last category is where most of the day to day variation between two similar people comes from, and it is also the one that quietly shuts down when you are tired, stressed or eating very little.
What works
1. Build and keep muscle
Muscle is metabolically active tissue and it is where most of the glucose in your blood ends up. Two strength sessions a week is the single most effective long term change most people can make, and it matters more with every decade. It also protects your metabolic rate during weight loss, which is when it usually falls.
2. Eat enough protein
Protein costs more energy to process than carbohydrate or fat, and it is the most filling of the three. Spreading it across meals, rather than loading it all at dinner, supports muscle better and steadies appetite through the day. Aim for a decent portion at breakfast, which is where most people are short.
3. Move more outside exercise
A daily walk, standing calls, stairs, carrying your own shopping. This category can differ by several hundred calories a day between two people with identical gym habits, and it is far easier to sustain than an extra class.
Want this built around your routine? A four week personalised programme with four private sessions is The Metabolic Code.
4. Sleep properly
Short sleep reduces insulin sensitivity, raises appetite, pushes food choices towards quick energy and reduces the spontaneous movement described above. You cannot out eat or out train it, and it is free.
5. Stop the very low calorie cycles
Repeated crash dieting costs muscle, and muscle is the thing you were trying to protect. Your body also adapts by reducing movement and downregulating non essential functions. Slower and steadier genuinely does keep more of your metabolic rate intact.
What does not work
- Green tea, chilli and caffeine as a strategy. They nudge energy expenditure by an amount too small to change your weight. Enjoy them, do not rely on them.
- Eating six small meals to keep the metabolism stoked. Total food matters. Meal frequency mostly affects appetite, and for some people constant eating makes it worse.
- Metabolism boosting supplements. If any worked as advertised, they would be medicines.
- Detoxes. Your liver and kidneys already do this and they are not waiting for a juice.
The honest bit about age
Research on large populations suggests energy expenditure is more stable through adult life than people assume, with the clear decline arriving later than the usual story about your thirties. What does change is muscle mass, daily activity and sleep. In other words, the slowdown people feel is largely the sum of things that can be worked on, rather than a fixed penalty for getting older.
Where to start this month
- Two strength sessions a week, even twenty minutes each.
- Protein at breakfast, every day.
- A walk after your largest meal.
- A consistent sleep window, including weekends.
Four changes, none of them dramatic, all of them compounding. If hunger and energy crashes are your main problem, read our guide to eating with insulin resistance next.
Want accountability rather than another list? Four private sessions and a personalised strategy: see The Metabolic Code.
Written by Suzan Raad, nutritionist and author of Epigenix, Epigenetic Awakening, Epigenetic Diet and Back to Babylon, and co-founder of 360 Degree Clinic in Surbiton, London. More about Suzan.
This article is nutrition and lifestyle education. It does not diagnose or treat any condition and does not replace advice from your doctor. If your symptoms are new, severe or persistent, please speak to a medical professional.
