How the visualizer works
At a fixed height, body volume grows roughly in line with weight, so the width of the figure scales with the square root of BMI. The shape widens most at the waist and hips, where most people gain and lose fat first, and least at the neck and ankles.
The figure is based on BMI alone. Two people at the same BMI can look very different depending on muscle mass.
BMI categories
The World Health Organization defines adult BMI categories as:
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5-24.9 | Healthy weight |
| 25-29.9 | Overweight |
| 30 and above | Obesity |
Why the scale does not tell the whole story
When you lose fat and gain muscle at the same time, your shape changes more than your weight. Muscle is denser than fat, so the same weight takes up less space.
That is why body measurements and progress photos are better at showing change than a figure drawn from weight. Photos taken in the same light and pose every few weeks show your real body, not an average one.
Setting a realistic goal
A healthy rate of loss is about 0.5-1% of body weight per week. Losing 5-10% of your weight already brings meaningful health benefits, even if you are still above the healthy BMI range.
Healthy weight for height chart
The visualizer shows your healthy weight range from BMI 18.5 to 24.9. Here is the same range for common heights.
| Height | Healthy weight (kg) | Healthy weight (lb) |
|---|---|---|
| 150 cm (4'11") | 41.6-56.0 | 92-123 |
| 155 cm (5'1") | 44.4-59.8 | 98-132 |
| 160 cm (5'3") | 47.4-63.7 | 104-140 |
| 165 cm (5'5") | 50.4-67.8 | 111-149 |
| 170 cm (5'7") | 53.5-72.0 | 118-159 |
| 175 cm (5'9") | 56.7-76.3 | 125-168 |
| 180 cm (5'11") | 59.9-80.7 | 132-178 |
| 185 cm (6'1") | 63.3-85.2 | 140-188 |
| 190 cm (6'3") | 66.8-89.9 | 147-198 |
| 195 cm (6'5") | 70.3-94.7 | 155-209 |
Why the same weight looks different on two people
BMI treats every kilo the same, but bodies do not. Four things change how the same weight looks:
- Muscle: muscle is denser than fat, so a muscular person looks smaller at the same weight.
- Where you store fat: some people carry it around the waist (apple shape), others on the hips and thighs (pear shape).
- Frame and height: broad shoulders and hips carry weight differently from a narrow frame.
- Water: salt, carbs and hormones can shift a few kilos of water from day to day without any change in fat.
How to see your real body change
That is why a tape measure tells you more than a figure drawn from weight. Our body fat calculator and waist-to-hip ratio calculator turn a few measurements into numbers you can track.
Progress photos are the most honest body visualizer there is, and Bodly keeps yours side by side with your weight and measurements. A few rules make them comparable:
- Same place, same light, same time of day, ideally in the morning.
- Same poses: front, side and back, arms relaxed.
- Same clothes, fitted enough to show your shape.
- Every two to four weeks. Weekly changes are too small to see.
- Compare side by side, first photo against latest, not one week against the next.