The Bodyfat Guide
Everything you need to know to measure and lose bodyfat.
Updated November 10, 2026. 19 guide pages, 30 questions, 9 myths, from 215 published sources.
How many calories do you need?
Sex
Heightftin
The questions people ask
Belly fat
- Can you lose belly fat?Yes, but not with sit-ups. Belly fat comes off when you lose fat all over, and the deep fat around your organs tends to shrink first. Eat less, lift and walk.
- How do I know if I have visceral fat?Measure your waist. Over 40 inches for a man or 35 for a woman, your risk of heart disease and diabetes goes up. A scale's visceral number is only a rough guess.
- Is cortisol belly real?Sort of. Far too much cortisol, as in Cushing syndrome, does put fat on the belly. Everyday stress goes with more belly fat in studies, but nobody has shown it causes it.
- Why do women gain belly fat in menopause?Because fat gain speeds up and muscle slips in the years around the last period, often at the same weight, and more fat goes deep in the belly. Lift and eat protein.
Food and drink
- Are there foods that burn fat?No food burns fat. A few help you eat less, mainly protein, which costs the most to digest, and fiber and vegetables, which fill you up for fewer calories.
- Do carbs make you fat?No. In a year-long trial of 609 adults, low-carb and low-fat dieters lost about the same weight. Total calories decide fat loss, so pick the diet you can keep.
- Does alcohol make you fat?It can. Alcohol has 7 calories a gram and your body burns it first, so fat burning stalls for hours. Light drinking isn't clearly tied to weight gain. Heavy drinking is.
- Does eating at night make you fat?Not by itself. A calorie at 9 pm counts the same as one at 9 am. Late eating can make you hungrier and invites extra snacks, so closing the kitchen after dinner helps.
- Does intermittent fasting burn more fat?No more than eating less the usual way. In a year-long trial, an eating window plus a calorie cut lost about the same as the calorie cut alone. Use it if it helps.
- Does sugar make you fat?Not more than other calories. When trials swapped sugar for starch at the same calories, weight didn't change. Sugar matters because it's easy to eat a lot of it.
- How much protein do I need to lose fat?1.2 to 1.6 g per kg of your weight a day, about 100 to 130 grams at 180 pounds. Under that is too low, and many people are. Lean lifters need more.
Exercise
- Can you lose fat and gain muscle at the same time?Yes. It shows most clearly in people new to lifting, and in trained lifters with the right plan. Lift with a plan, eat plenty of protein and track your waist.
- Do you lose muscle in a calorie deficit?Some, if you only diet. About a quarter of weight lost by diet alone is lean mass. Lift, eat enough protein and lose slowly, and you can keep most of it.
- Is cardio or lifting better for fat loss?Do both. In an 8-month trial, cardio took off more fat and lifting added muscle. Doing both did best on the waist. Food still does most of the work.
- Why am I not losing weight even though I work out?Because workouts burn less than they feel like, and the body makes up some of it. Five workouts a week for 10 months took off 4 to 6% of weight. Food is the bigger lever.
Measuring and the scale
- Are bodyfat scales accurate?Not for one morning. In a lab test, home scales missed by about 3 to 12 points, depending on the model. They track change better. Trust the monthly trend.
- How do I measure bodyfat at home?With a tape measure, the same way each month. The Navy tape method lands within a few points. A bodyfat scale adds a daily trend. For one precise number, get a DEXA scan.
- Is my plateau real or water weight?If it's under two or three weeks, it's probably water hiding fat loss. If your weekly average has been flat for a month while you log everything, it's real.
- Why is my bodyfat not going down when I'm losing weight?Usually because the percentage moves slowly and your scale's estimate is noisy. If your weight and your waist are both falling over a month, you're losing fat.
Your body and metabolism
- Am I losing fat or muscle?Mostly fat, if your lifts are holding, your waist is shrinking and you're losing under about 1% of your weight a week. Falling strength with fast loss is the muscle sign.
- Am I skinny fat?Maybe, if your weight is normal but your waist is big or your bodyfat is high. Don't start with a diet. Lift weights and eat enough protein at your usual calories.
- How many calories are in a pound of fat?About 3,500. But cutting 3,500 calories won't always take off a pound, because a smaller body burns less. In trials people lost about a quarter less than the rule.
- Is 20% bodyfat good?For a man, 20% is average and close to the healthy range. For a woman, it's lean, in the range athletes sit in. US averages are about 28% for men and 40% for women.
- Where does fat go when you lose it?Mostly out through your lungs. Of every 10 pounds of fat you lose, about 8.4 pounds leave as carbon dioxide you breathe out, and the rest leaves as water.
GLP-1 drugs
- Do fat burner supplements work?Not in a way worth paying for. Most weight loss supplements are unproven, and the FDA keeps finding some laced with hidden drugs. Spend the money on food and a scale.
- Do GLP-1 drugs make you lose muscle?Some, as any big weight loss does. On tirzepatide about a quarter of the weight lost was lean mass, the same share as on diet alone. Lift and eat protein to keep more.
- What happens when you stop taking Ozempic?Most people regain much of the weight. A year after stopping semaglutide in its main trial, two thirds of the loss was back. Plan any stop with your doctor.
Keeping it off
- How long does it take to lose bodyfat percentage?About 2 to 3 months for every 5 points, for most people losing about a pound a week. Your size sets the exact time, and slower is better for keeping muscle.
- Why do most people regain the weight?Because the body burns less after a diet and old habits come back. On average more than half the weight lost is back within two years. Plan the keeping too.
- Why has my weight loss slowed down?Because a smaller body burns less, and the body trims its burn a bit more on top. The same diet that once lost a pound a week now loses less. Re-set your calories.
Myth or fact?
No Does the fat-burning zone matter?
No Can you burn fat from one spot?
No Does eating breakfast speed up your metabolism?
Sort of Does eating too little put you in starvation mode?
Not the way you think Does insulin from carbs make you store fat?
Not until about 60 Does your metabolism slow down after 30?
Quick calculators
Your calories
How many calories a day hold your weight where it is.
Your protein
Your typical range for losing fat, and the line under which it is too low.
Calories to lose, and your date
What to eat each day to reach your goal, and the day you get there.
Bodyfat from a tape
Three tape measurements give your bodyfat as a range.
Losing fat or muscle?
Two weigh-ins in. What you lost in fat and in lean mass out.
Waist check
Your waist against the US lines for heart and diabetes risk.
The Fat Loss Protocol
Twelve habits, tracked for you
The most powerful way to lose bodyfat safely: twelve requirements, tracked for you, with free cheat sheets for the first seven.
See the twelve habits
The two guides
The strategy guide
Everything you need to know about fat loss
How fat loss works, how to eat less without being hungry, your calories, pace and protein, how to move, how to track it, and the mistakes that stall it.
Keeping it off
How to keep the weight off after you lose it
The second guide. The first months after a diet, your new maintenance calories, why your burn drops, when to take a diet break, and bulking after a cut.
Drugs, a coach or on your own
GLP-1 drugs
How GLP-1 drugs work for fat loss
How Ozempic, Wegovy, Mounjaro, Zepbound and Saxenda work, how much weight people lost in the trials, what happens to muscle, and what happens when you stop.
Natural or guided
Natural vs guided fat loss: on your own, with a coach or with a drug
Losing fat on your own, with a coach or with a GLP-1 drug. What each adds, how much people lost in trials, who each suits, and why the habits matter in all three.
Weigh in each morning on a Withings or any Apple Health scale and Gyroscope logs your weight and bodyfat on its own, free on any plan. Open Gyroscope
