Several foods, drinks, and supplements can give your metabolism a measurable nudge, though none of them replace the fundamentals of diet and exercise. The most effective options work by increasing thermogenesis (the heat your body produces while processing energy), improving how efficiently you burn fat, or supporting the hormones and enzymes that regulate your metabolic rate. Here’s what the evidence actually supports.
Protein Has the Largest Thermic Effect
Your body burns calories just digesting food, and protein demands far more energy to process than anything else on your plate. Protein burns 20 to 30 percent of its own calories during digestion, compared to 5 to 10 percent for carbohydrates and less than 3 percent for fat. That means if you eat 300 calories of chicken breast, your body spends 60 to 90 of those calories just breaking it down and absorbing it.
This thermic advantage makes protein the single most impactful dietary change for metabolism. Swapping some of your carbohydrate or fat calories for protein-rich foods like eggs, fish, lean meat, legumes, or Greek yogurt creates a consistent, compounding effect throughout the day. Protein also helps preserve muscle mass, which matters because muscle tissue burns more calories at rest than fat tissue does.
Caffeine
Caffeine is one of the most studied metabolic stimulants, and it works. A dose as small as 100 mg, roughly one cup of coffee, increases your resting energy expenditure by 3 to 4 percent. That’s a modest but real bump, and it stacks up over the course of a day if you drink coffee or tea regularly.
The FDA and the European Food Safety Authority both consider up to 400 mg per day safe for adults, which translates to about four standard cups of coffee. Beyond 500 mg, side effects like anxiety, rapid heartbeat, and sleep disruption become more common. At extremely high doses (around 1,000 mg for a 150-pound person), caffeine becomes toxic and can cause nausea, vomiting, and seizures. Stick to moderate amounts from coffee, tea, or yerba mate rather than concentrated supplements or energy drinks.
Green Tea Extract
Green tea contains compounds called catechins that boost fat burning beyond what caffeine alone can do. In a study published in the American Journal of Clinical Nutrition, green tea extract increased fat oxidation by 17 percent compared to a placebo, and a greater share of total energy expenditure came from burning fat rather than carbohydrates. Drinking green tea as a beverage is considered safe and delivers these catechins in moderate amounts alongside a mild caffeine boost.
Concentrated green tea extract supplements are a different story. High-dose extracts, particularly those containing over 800 mg of the active catechin EGCG, have been linked to liver damage, nausea, and increased blood pressure. These problems are more likely when supplements are taken on an empty stomach. If you opt for an extract, take it with food and choose a product with a moderate catechin dose.
Capsaicin From Hot Peppers
The compound that makes chili peppers hot also fires up your metabolism. Capsaicin triggers thermogenesis, forcing your body to produce extra heat and burn additional calories. One clinical study found that a low-dose capsaicin supplement increased metabolic rate enough to burn an extra 116 calories per day. That’s roughly equivalent to a brisk 20-minute walk, just from a supplement.
Short-term use at doses up to 33 mg per day for four weeks, or 4 mg per day for 12 weeks, appears safe. Higher doses can cause stomach discomfort. You can also get capsaicin naturally by adding cayenne pepper, jalapeños, or other hot peppers to your meals. The metabolic effect is smaller from food quantities than from concentrated supplements, but it adds up alongside other strategies.
Water
This one surprises most people. Drinking 500 ml of water (about 17 ounces, or a standard water bottle) increases your metabolic rate by 30 percent. The effect kicks in within 10 minutes and peaks around 30 to 40 minutes after drinking. Your body expends energy warming the water to body temperature and processing it, a phenomenon called water-induced thermogenesis.
The calorie burn from a single glass is small in absolute terms, but drinking several glasses of cold water throughout the day creates a steady, passive metabolic boost that costs you nothing and has no side effects. It’s one of the simplest interventions on this list.
Omega-3 Fatty Acids
Fish oil supplements containing omega-3 fatty acids can produce a surprisingly large increase in resting metabolic rate, at least in certain populations. A 12-week study of healthy older women found that supplementing with fish oil (providing 2 grams of EPA and 1 gram of DHA daily) increased resting metabolic rate by 14 percent. Most of that increase, about 11 percent, was already visible by week six.
This study focused on older women, so the effect may be smaller in younger people or men. Still, omega-3s support metabolic health through multiple pathways, including reducing inflammation and improving how your cells use insulin. Good dietary sources include salmon, sardines, mackerel, and walnuts, though reaching the doses used in studies typically requires a supplement.
B Vitamins and Iron
Your metabolism runs on enzymes, and many of those enzymes can’t function without specific vitamins and minerals acting as helpers. B vitamins are especially critical. Vitamins B1, B2, and B3 are directly involved in the chemical reactions that convert food into usable energy. Pantothenic acid (B5) helps transport the molecular fuel that powers your cells. Without adequate levels of these vitamins, your metabolic machinery slows down.
Iron plays a different but equally important role. It’s required for producing thyroid hormones, which act as your body’s metabolic thermostat. Iron deficiency reduces circulating levels of both major thyroid hormones and impairs the conversion of the less active form into the more active one. The result is a sluggish metabolism that makes weight management harder. Women, vegetarians, and people with heavy menstrual periods are most at risk for iron deficiency.
If you’re already getting enough of these nutrients from your diet, supplementing won’t boost your metabolism further. But if you’re deficient, correcting the gap can restore your metabolic rate to where it should be. A blood test can identify deficiencies worth addressing.
Soluble Fiber
Fermentable soluble fiber, the kind found in oats, beans, lentils, apples, and flaxseed, influences metabolism indirectly by increasing production of a gut hormone called GLP-1. This hormone improves how your body handles blood sugar, stimulates insulin release, and slows gastric emptying so you feel full longer. Research shows that diets high in fermentable fiber significantly increase GLP-1 secretion compared to diets with the same total fiber from non-fermentable sources like cellulose.
GLP-1 is the same hormone targeted by newer weight management medications. While fiber won’t produce effects as dramatic as a prescription drug, consistently eating 25 to 30 grams of fiber per day supports the metabolic hormones that regulate energy use and appetite.
What Probably Won’t Help
L-carnitine is heavily marketed as a fat-burning supplement because it helps transport fatty acids into the part of your cells where they’re burned for energy. This is a real biological function, but supplementing with extra L-carnitine doesn’t appear to speed up the process. Clinical trials have not shown meaningful improvements in fat metabolism or weight loss in people who aren’t deficient.
Many “metabolism booster” blends sold online combine small amounts of caffeine, green tea, and capsaicin with unproven ingredients at doses too low to produce the effects seen in studies. If you want the benefits of these compounds, you’re better off getting them individually at effective doses through food, beverages, or single-ingredient supplements where you can control what you’re taking.
Stacking Strategies for the Biggest Effect
No single item on this list will transform your metabolism on its own. The practical approach is combining several of them into your daily routine. A high-protein breakfast, a few cups of coffee or green tea, plenty of water throughout the day, adequate fiber from whole foods, and a fish oil supplement if you don’t eat fatty fish regularly. Add some spice to your meals if you enjoy it. Make sure you’re not low on B vitamins or iron.
Together, these small effects compound. A 3 to 4 percent bump from caffeine, an extra 100-plus calories from capsaicin, the thermic advantage of protein at every meal, and passive calorie burn from water adds up to a meaningful difference over weeks and months. None of it replaces strength training and an active lifestyle, which remain the most powerful long-term metabolic interventions. But for people asking what they can take, these are the options with real evidence behind them.