How to lose body fat: the short list that does it, and how to keep your muscle along the way

Body fat and body weight aren't the same number. The scale counts everything: fat, muscle, water and whatever you ate last night. Losing fat is the goal most people mean, and the way to get there is to lose fat while keeping the muscle you have. What follows is the short list the research supports, each in a paragraph, with the page on this site that covers it properly.

It's a page about how fat comes off, not a promise about how much or how soon. The studies below measured groups of people. If you're stuck already, start with why you can't lose fat; if you want to build muscle at the same time, that's body recomposition.

1. Eat a little less than you burn

This is the part that takes fat off. A 2012 consensus statement on energy balance gives the principle: body weight change is associated with an imbalance between the energy in the food you eat and the energy your body spends.¹ In practice: estimate your maintenance calories, eat a little under them, and adjust from what your weekly trend does. The starting numbers and how to adjust them are on calories and protein.

Food and training work better together than either alone. A 2014 meta-analysis of eight trials with 1,022 adults, most of them women, found that programs combining diet and physical activity produced more weight loss at 12 months than diet alone, and that programs based on physical activity alone were less effective than the combination in both the short and the long term.²

2. Keep lifting: it's what keeps your muscle

A calorie deficit can take muscle along with fat; lifting gives your body a reason to hold on to it. A review of weight loss and muscle found that diet-induced weight loss reduces muscle mass, and that both endurance and resistance exercise help preserve it, with resistance exercise also improving strength.³ In a 2018 analysis of six trials in older adults with obesity, lifting three times a week during a calorie cut prevented almost all of the lean mass that the cut alone cost, and the fat loss was not significantly different with or without it.⁴ The American College of Sports Medicine's position stand puts the trade this way: resistance training doesn't add to the weight you lose, but it may increase fat-free mass and the loss of fat mass.⁵ If you don't lift yet, start with how to start lifting weights; the full list is how to build muscle.

3. Eat enough protein

This site's number for people who lift is 0.7 to 1 gram of protein per pound of bodyweight a day, about 1.6 to 2.2 grams per kilogram.^6,7 Aim toward the higher end while you're losing fat, because protein helps protect muscle when calories are lower.^8,7 How to reach it every day: calories and protein, or put your bodyweight into the protein intake calculator.

4. Move more, and treat cardio as a helper

The World Health Organization's guideline for adults is 150 to 300 minutes of moderate activity a week, or 75 to 150 of vigorous, plus regular muscle-strengthening activity.⁹ That's an activity amount, not a fat-loss target. Cardio adds to the energy you use, but on its own it's a small lever: a 2017 meta-analysis of 31 studies found interval and steady cardio about even for body fat, and concluded that neither produced clinically meaningful reductions in body fat over the short term.¹⁰ Daily steps are the easiest part to keep: walking for fat loss. How much cardio, in minutes: how much cardio per week.

5. Sleep

The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults sleep seven or more hours a night on a regular basis.¹¹ It matters for what you lose. In a small 2010 trial, 10 overweight adults spent two weeks on the same moderate calorie cut twice, once with 8.5 hours in bed and once with 5.5; with less sleep, less of the weight they lost came from fat and more from fat-free mass.¹² That was 10 people over 14 days, so it shows a direction, not a size.

6. Judge it by the trend

The scale is noisy, so one weigh-in tells you little. Use a weekly weight average, a waist measurement taken the same way each time, photos in the same light, and your lifts. If the lifts hold, you're probably keeping your muscle; if the waist comes down, fat is leaving. How to know it's working lays the measures out.

Common questions

How do you lose body fat fast?

This page doesn't give a rate, because no honest page can give yours. What the trials above do show is the cost of pushing: diet-induced weight loss takes muscle with it, training helps keep it, and short sleep shifted more of the loss onto fat-free mass.^3,12 The version that keeps your muscle is a small deficit, lifting, enough protein and sleep, held for as long as it takes.

How do you lose body fat without losing muscle?

Keep lifting, keep protein toward the higher end of the range and sleep. In the 2018 analysis, lifting during a calorie cut prevented almost all of the lean-mass loss.⁴ Those were older adults with obesity, but the direction matches the review above.³

How do you lower your body fat percentage?

Body fat percentage is the share of your weight that is fat, so it comes down two ways: less fat, or more muscle at the same fat. The list above does both. This page doesn't set a percentage to aim for; track the same measures, taken the same way, over time.

Can you lose body fat without losing weight?

Yes, if you build muscle while you lose fat, which is called body recomposition. The scale may barely move while your waist and your lifts change. Who it works for and what it takes: body recomposition.

Is it different for women?

The list is the same. Most of the 1,022 people in the 2014 meta-analysis were women.² Training for women specifically: strength training for women.

What about belly fat or a six pack?

Those are the same method plus one question each: whether training one spot takes fat off it (how to lose belly fat) and how the abs themselves get built (how to get a six pack).

If you'd rather have someone read the trend

The list is short; holding it through restaurants, weekends and bad weeks, and knowing what to change when the trend stalls, is the hard part. Coaching is the version where your workouts live in Trainerize, built around the days you actually have, and someone reads your weigh-ins, photos and logged workouts every week and adjusts the plan. Fat loss coaching explains how that works, and apply is the first step. Otherwise: take your waist measurement today and write it down.