Should you count calories or count macros? Cut fat or cut carbs? Eat double the recommended amount of protein? Triple? Maybe just attach to a gentle IV of protein shake?

Really, it shouldn’t be so difficult to work out which eating regimen will set fire to fat while maintaining muscle. Fortunately, the International Society of Sports Nutrition just released its position paper, which combs through all existing scientific studies to report how every diet will affect your body composition. Here, we’ve pulled five of the foremost six-pack-friendly diets and streamlined how they’re great, also as why they could be right (or wrong) for you—according to the hard science.

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1. reducing diet

Defined as: Only consuming 800 to 1,200 calories each day .

Pros: the only purpose of limiting your daily calories (and pushing the boundaries of sanity) is to reduce ASAP—and the study analysis says it works, while also preserving the maximum amount lean muscle mass as possible.

Cons: In our experience, capping your calories low will probably mean tons of internal strife and stress. Plus, we’re big fans of enjoying food rather than fearing it, and 800 calories doesn’t leave much room for satisfied taste buds. Lastly, if you’re currently eating double to triple this amount of food, dropping to a daily caloric intake this low can tank your metabolism and truly slow weight loss quite switching to at least one of those other diets might. (Curious? Here’s why starving yourself won’t assist you reduce .)Evgenija Lanz / EyeEm2 / 5

2. diet

Defined as: Getting only 20–30% of daily calories from fat; the remaining 80–70% are split between protein and carbs, typically with a stress on carbs.

Pros: Advocated by the Institute of drugs , a diet (or high-carb, counting on your perspective) is predicated round the concept curtailing on the foremost calorie-dense macro will assist you eat fewer calories overall. And studies do show switching to a diet can assist you lose body fat quickly, though not necessarily long-term.

Cons: Eating this manner perpetuates the outdated concept dietary fat is that the enemy of body fat. And it isn’t necessarily better than other diets: One study within the American Journal of Clinical Nutrition compared high-protein, normal protein, high-fat, and low-fat diets, and located no significant difference in fat loss among the groups at six months or two years (though all did end in some fat loss). What’s more, while the low-fat group was alleged to keep its intake of the macro at 20%, actual intake was closer to 26-28%, suggesting that sticking to a strict diet is quite difficult and potentially unrealistic for many .Claudia Totir/Getty Images3 / 5

3. Low-carb diet

Defined as: Getting 15–40% of daily calories from carbs; the remaining 85-60% is split between protein and fat.

Pros: Compared to eating a standard diet, switching to a low-carb diet can significantly reduce body fat, studies show. Cap your carb intake at 20% of daily calories and therefore the weight-loss results are even stronger—plus, you’ll reduce your risk for heart condition and stroke. Some research suggests low-carb diets are even better than low-fat diets: One study in Annals of general medicine found that folks who limited their carbs lost eight more pounds than those that crop on fat. If you narrow back on carbs enough, your body learns to burn fat as fuel instead. Studies are mixed on how low-carb diets affect performance, but some evidence suggests that endurance performance can actually improve among people whose bodies adapt to fat-burning fairly easily.

Cons: Teaching your body to burn fat rather than carbs takes time, so you’ve got to twiddling my thumbs while you are feeling sluggish during the weeks it takes to become fat-adapted. And not every one burns fat as efficiently as carbs, so your endurance may never qualify (though, as we said before, others actually see an improvement here.) Without carbs, your body’s ability to get explosive energy will presumably decline, so if you’re keen on sprinting or HIIT, you would possibly got to consume more carbs than other low-fat dieters. And while you’ll probably lose body fat, this type of diet is really keeping you focused on the incorrect macro: Studies have proven that the upper protein aspect of a low-carb diet helps promote weight loss, instead of the lower carb count.Gareth Morgans/Getty Images4 / 5

4. Ketogenic diet

What it is: but 10% of daily calories from carbs, 10-30% from protein, 60-80% from fat.

Pros: Technically a subtype of low-carb diet, the keto diet is unique: By depriving your body of carbohydrates, you not only force your body to become fat-adapted, but also, if you retain protein low also , elevate your levels of ketone bodies, which is essentially a symbol your body is running on fat. The keto diet puts you during a unique metabolic state called ketosis wherein your brain burns ketones rather than glucose—and, in doing so, supposedly results in clearer thinking. Physically, eating such a high amount of fat significantly increases your body’s ability to burn body fat, consistent with the study analysis. Research also shows keto athletes have a better VO2 max, and are ready to lose fat without losing strength or power.

Cons: that very same study on the perks of being a keto athlete also found those self same dieters had a lower exercise economy (how efficiently you employ oxygen while moving). And whereas just about every other diet offers flexibility within the macro range, eating a couple of too many grams of carbs or protein will knock your body out of ketosis, so you’ve got to be pretty committed to ascertain the perks of this one. Lastly, the low protein count required to remain in ketosis could also be holding you back here: A study analysis in Nutrition, Metabolism, and Cardiovascular Diseases found upping protein on a keto diet by just 5% tripled fat loss.Andrew Scrivani/Getty Images5 / 5

5. diet

What it is: a minimum of 25% of daily calories from protein.

Pros: the foremost consistently beneficial of all diets here, study after study shows that upping your protein intake can help significantly reduce body fat and build lean muscle. For example: Guys who ran sprint intervals, did resistance training, and ate a diet of two .4g of protein per kg of bodyweight per day (roughly 1g per lb of bodyweight) gained 1.2kg of lean muscle and lost almost 5kg of fat in only four weeks, consistent with a study within the American Journal of Clinical Nutrition. If you narrow calories but eat high protein, the macro can help prevent your metabolism from plummeting and help keep hunger cornered , since protein is so satiating. The study analysis also confirmed that eating plenty of protein stuff doesn’t cause you to realize weight or harm any internal systems, despite myths.

Cons: With the main target on protein, it’s easy to forget you would like to eat enough fat or carbs to fuel your workouts, so keep an eye fixed on your energy levels and other macros. And that’s the sole real downside. the sole other con the study analysis found: High protein is so effective in making you less hungry that it’d hurt your efforts to realize weight.