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Rumour has it all kinds of things can ignite your metabolism, from chugging caffeine to pumping iron. Here’s what can light your fire… And what’s just charred crap.

Like “Yas, queen”, metabolism is a term that gets tossed around a lot by people who don’t really understand it. Even experts disagree on how it works. But no one disputes that it’s key – maybe the major key – to successful weight loss. Truth: your metabolism is what combusts the food you eat into energy. It can do this in slo-mo or F1 mode – and even when you’re not lifting a finger, it’s still idling, making your heart beat and nails grow. That behind-the- scenes action stems from your innate resting metabolic rate or RMR. A fast RMR (thank you, genetics!) is what lets you eat a tub of Häagen-Dazs without becoming a chunky monkey. RMR accounts for more than half of the kilojoules you burn; the rest is in your hands. And you can gun your metabolism into higher gear – just not in all the ways you’ve heard.

Have a need, a need for speed? We examined the most hyped-up “cures” for a sluggish metabolism to determine what’s possible, plausible, practical – or just plain psshhh when it comes to those metabolism boosters…

Extreme dieting

Cutting kilojoules, bad for weight loss – say whaaat? Truth is, going too low sends your body into starvation mode and slows your metabolism as your body clings to every last morsel. Worse, the effect may last months, years – nobody really knows how long.

READ MORE: 10 Things That Makes Your Metabolism Slow Down

Mental energy

Sadly, brainpower doesn’t run on carbs. One-fifth of your RMR does go to maintaining your mind, but that amount is a constant; you won’t use any more solving calculus equations than you do watching House of Cards.

Spicy foods

It’s often said that capsaicin – the compound that makes chilli hot – can fire up fat burning. While technically true, the payoff is so tiny that pros consider it negligible. (But there are other good reasons to eat the stuff.)

READ MORE: 6 Foods That Fire Up Your Metabolism And Burn More Fat

Cigarettes

We really hate rating this anything above negative bajillion, but cigs may speed up your metabolism. But only a tiny bit and only for a short while. Given that a quarter of smokers will die from their habit, we recommend quitting while you’re ahead.

Coffee

The caffeine stimulant helps shake your metabolic engine into high gear for about three hours after consuming it. And around two cups pre-workout can also help you torch up to 15 percent more kilojoules. Caveat: your bod will get used to the buzz, so several cups a day could blunt the rewards.

READ MORE: 4 Things To Avoid If You Want To Keep Your Metabolism Burning

Temperature

Being above shivering but below comfortable (right around the 15°C mark) can bump up your metabolism. Why? The “good” kind of fat, called brown adipose tissue, helps regulate body temperature by turning kilojoules into fuel.

Green tea

Healthy compounds known as catechins found in tea have been shown to stoke your internal food furnace. It can’t be decaf, but down two to three cups a day with meals and you can incinerate 335 kilojoules. Easy!

READ MORE: 5 Quick Ways To Speed Up Your Metabolism

Late nights

Weirdly enough, running on only five hours of sleep a night led people in one study to burn slightly more kilojoules during the day. Too bad those study subjects ate more than they blasted during that mild metabolism boost… And gained just under one kilogram in a week.

Paleo

Even though it seems too awesome to be true, just digesting food helps shave kilojoules (really!). If your diet is heavier on protein – a nutrient that uses between 20 and 30 percent of a food’s kilojoules to digest, compared with just five to 15 percent for carbs – you’ll get a metab surge.

READ MORE: 5 Ways To Boost Your Metabolism If Your Thyroid Is Giving You Problems

Strength training

When it comes to strength training toned abs don’t just look hot, they also annihilate kilojoules when you’re sitting around. That’s because muscle is metabolically active tissue, which means it’s always “on.” For every kilo of flab you turn into muscle, you burn an additional 56kJ a day – without even flexing!

Looking for more info on metabolism boosters? Here are 10 things that actually make your metabolism slow down, plus five quick tricks for speeding it up.