How much should I weigh is the first question most people bring to a health site, and the honest answer is a range, not a number. For a given height there is a band of weights that the CDC and WHO count as healthy, a second band from the ideal weight formulas doctors use, and two measurements, body fat and waist, that say more about health than the scale does. The six tools below give each of those figures from your own measurements in a few seconds. Underneath them is what each figure means, what shifts after 40, and every guide on this site for changing the number when you want to.
Body & Weight
Your Healthy Weight Is a Range for Your Height
The CDC and WHO define a healthy weight for adults as a body mass index between 18.5 and 24.9. BMI is your weight in kilograms divided by your height in metres squared, so for any height it turns into a weight range. At 165 cm (5 ft 5 in) that range runs from about 50 to 68 kg (111 to 150 lb). At 175 cm (5 ft 9 in) it runs from about 57 to 76 kg (125 to 168 lb). The BMI calculator shows the range for your exact height next to your number.
A range this wide is the point. Two people of the same height can sit 18 kg apart and both be at a healthy weight, because frame, muscle and where fat is stored all differ. BMI is a screening number: it cannot tell muscle from fat, and it says nothing about the waist. That is why the next three measures exist.
| Measure | What it tells you | The line that matters |
|---|---|---|
| BMI | Whether your weight sits in the range linked to good health for your height | 18.5 to 24.9 is the healthy range for adults |
| Ideal weight | A second range from four clinical formulas built on height and sex | The formulas differ by several kilograms; treat their spread as the range |
| Body fat | How much of your weight is fat rather than muscle, bone and water | Women: 25 to 31% is average, 32% and above is high. Men: 18 to 24% average, 25% and above high |
| Waist | Where fat is stored, which predicts heart disease and type 2 diabetes risk better than weight alone | More than 35 in (88 cm) for women or 40 in (102 cm) for men raises risk; a waist to hip ratio of 0.85 or more (women) or 0.90 or more (men) is the WHO cutoff for substantially increased risk |
Ideal Weight Formulas Give a Second Opinion
The Devine, Robinson, Miller and Hamwi formulas were written for drug dosing and insurance tables, and each gives one figure from height and sex. Devine, the most used, starts at 45.5 kg for a woman of 5 ft and adds 2.3 kg per inch above that; for a man it starts at 50 kg. Because the four disagree by several kilograms for the same person, their spread is more useful than any single result: if your weight sits inside it, the formulas agree with you. The tool shows all four and the range they make.
Body Fat and Waist Say More Than the Scale
Two people at the same weight and height can carry very different amounts of fat, and the one with more muscle is in better shape by every health measure. A body fat estimate from tape measurements, the method the US Navy uses, separates the two. Women naturally carry more fat than men: 25 to 31% counts as average for a woman and 32% and above as high, against 18 to 24% and 25% for a man.
Where the fat sits matters as much as how much there is. Fat around the organs, which shows as a larger waist, is the kind linked to heart disease and type 2 diabetes. The NHLBI puts the line at a waist of more than 35 inches (88 cm) for women and 40 inches (102 cm) for men, whatever the BMI. The WHO reads the same risk from the waist to hip ratio, with cutoffs of 0.85 for women and 0.90 for men. A tape measure, then, answers a question the scale cannot.
What Changes After 40
The scale can stay still while the body underneath it changes. Muscle mass falls by roughly 3 to 8% a decade after the age of 30. Around menopause the shift is sharper: in the Study of Women’s Health Across the Nation, which measured body composition by DXA scan for years on either side of the final period, the rate of fat gain doubled from about two years before the final period and lean mass began to fall, and both continued until two years after it. Across that transition the share of body weight that was fat rose by 3.6 percentage points and the share that was lean fell by 1.9, independent of ageing itself.
So a woman who weighs the same at 52 as at 42 can have a larger waist and a higher body fat percentage than the number suggests. That is the case for measuring waist, body fat and lean body mass rather than weight alone after 40, and for the guides on starting weight training, on the daily habits that keep metabolism up, and on what the evidence says about supplements for perimenopause weight gain.
If You Want to Change the Number
The CDC’s advice is a gradual, steady loss of about 1 to 2 pounds (0.5 to 1 kg) a week, because people who lose at that pace are more likely to keep the weight off. Eating roughly 500 calories a day under what your body uses gives the lower end of that pace, and the calorie calculator works that out from your age, height, weight and activity. It never sets a target below 1,200 calories a day for women or 1,500 for men. Protein and strength work protect the muscle you have while the fat goes, which matters more the older you are.
The guides below are the whole of this site’s weight section. Each one is written against primary research and dated when it changes.
Start Here
- How to lose weight after 40 for women without starving
- Daily habits to boost metabolism after 40
- Why am I not losing weight in a calorie deficit?
- Weight loss plateau for women over 40: why it happens and how to break it
- Why weight jumps after a cheat day
- Intermittent fasting for women over 40: what the results look like
Eating
- High protein breakfasts for weight loss for women over 40
- High protein low carb meal plan for weight loss: a 7-day guide
- High protein legume recipes for weight loss
- Vegetarian high protein meal prep for weight loss
- Fibermaxxing for weight loss: what the science says
- The best diet for PCOS weight loss
- High protein meals weighed to your calorie target
Training
- How to start weight training for women over 40
- A gym workout plan for weight loss for women
- The best gym exercises for belly fat for women
- How many sets and reps for women to lose weight
- How to lose belly fat without exercise
Particular Situations
- How to keep muscle on GLP-1 while losing weight
- Supplements for perimenopause weight gain: what the evidence says
- How to lose weight on antidepressants
- How to lose weight after quitting smoking
- How to lose weight on night shift
- Losing weight while breastfeeding without losing milk supply
New guides land in the Weight Loss section, which lists every one with its date.
Frequently Asked Questions
How much should I weigh for my height?
Take the weight range that gives a BMI of 18.5 to 24.9 at your height as the healthy band; the BMI calculator prints it for your exact height. At 160 cm that is about 47 to 64 kg, at 170 cm about 54 to 72 kg, at 180 cm about 60 to 81 kg. Where you should sit inside that band depends on your frame and muscle, which is what the ideal weight and body fat tools add.
Is BMI or body fat percentage the better measure?
Body fat tells you more, because BMI cannot separate muscle from fat. BMI is quicker and needs no tape, which is why doctors use it first. The useful pairing is BMI plus a waist measurement: a healthy BMI with a waist over 35 inches (women) or 40 inches (men) still carries the risk that comes with fat around the organs.
Does my ideal weight change after 40?
The healthy BMI range and the ideal weight formulas do not change with age for adults, but what a given weight is made of does. Muscle falls by 3 to 8% a decade from 30 and fat gain speeds up around menopause, so the same weight at 50 tends to carry more fat and less muscle than at 35. After 40, a waist measurement and a body fat estimate say more than the scale.
How fast should I lose weight?
The CDC’s guidance is 1 to 2 pounds (0.5 to 1 kg) a week, which is a deficit of about 500 calories a day. Faster loss costs more muscle and is harder to keep. The calorie calculator gives a daily target and will not go below 1,200 calories for women or 1,500 for men.
My weight is in the healthy range but my waist is over the line. Which matters?
The waist. Fat stored around the middle raises heart disease and type 2 diabetes risk on its own, whatever the BMI says. The fix is the same as for weight loss in general, a modest calorie deficit, protein and strength training, and the waist usually comes down before the scale does much.
Sources
- Adult BMI Categories · CDC
- Aim for a Healthy Weight · NIH National Heart, Lung, and Blood Institute
- Waist circumference and waist-hip ratio: report of a WHO expert consultation · WHO
- Muscle tissue changes with aging · Volpi et al., Current Opinion in Clinical Nutrition and Metabolic Care (PMC)
- Changes in body composition and weight during the menopause transition · Greendale et al., JCI Insight (PMC)
- Steps for Losing Weight · CDC
- Body Fat Percentage: Charting Averages in Men and Women · American Council on Exercise
This page is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment.