The Complete Guide to Healthy Weight
How BMI, body fat, BMR and calories fit together — a practical, no-fads framework for reaching and maintaining a healthy weight, backed by the numbers.
The internet is drowning in weight-loss advice, most of it contradictory and some of it harmful. Underneath the noise, though, the science is refreshingly simple. This guide connects the key measurements — BMI, body fat, BMR and calories — into one clear, sustainable framework.
Step 1: Know where you’re starting
Two numbers give you a baseline.
Body Mass Index (BMI) is a quick screen comparing weight to height. It doesn’t measure fat directly, but for most people it’s a useful first check.
Use this converter to convert to the unit accepted by the calculator.
Example
This is a sample result, not your calculation. Enter your own values to replace it.
Enter your height and weight, then calculate your BMI.
Your BMI
—
Healthy weight range
A healthy weight for your height is —.
WHO adult classification (healthy BMI 18.5–24.9). BMI is a screening tool, not a diagnosis.
Check your entries
Enter your height and weight to calculate your BMI.
Body fat percentage is the better measure of composition, because it separates fat from muscle. A muscular person can have a “high” BMI yet low body fat. Use the body fat calculator alongside BMI, and the ideal weight calculator for a realistic target range for your height. The lesson: don’t fixate on a single number on the scale — look at the whole picture.
Step 2: Understand energy balance
Weight change comes down to one principle: energy in vs. energy out. Eat more energy (calories) than you burn and you gain weight; eat less and you lose it. Everything else — which diet, which foods, which schedule — is just a strategy for managing that balance.
Two numbers define your “energy out”:
- BMR (Basal Metabolic Rate) — the calories your body burns at complete rest. Find yours with the BMR calculator.
- TDEE (Total Daily Energy Expenditure) — your BMR multiplied by an activity factor. This is your real daily calorie need.
Use this converter to convert to the unit accepted by the calculator.
- Exercise: 15-30 minutes of elevated heart rate activity.
- Intense exercise: 45-120 minutes of elevated heart rate activity.
- Very intense exercise: 2+ hours of elevated heart rate activity.
Example
This is a sample result, not your calculation. Enter your own values to replace it.
Enter your age, gender, height, weight and activity level, then calculate.
The results show a number of daily calorie estimates that can be used as a guideline for how many calories to consume each day to maintain, lose, or gain weight.
- Maintain weight— — Calories/day
- Mild weight loss 0.5 lb/week— — Calories/day
- Weight loss 1 lb/week— — Calories/day
- Extreme weight loss 2 lb/week— — Calories/day
- Mild weight gain 0.5 lb/week— — Calories/day
- Weight gain 1 lb/week— — Calories/day
- Fast weight gain 2 lb/week— — Calories/day
Zigzag calorie cycling
Eating the same amount every day is not the only way to hit a weekly target. A zigzag week alternates higher and lower days around your maintenance figure, which some people find easier to stick to. Both weeks below come to the same total.
| Day | Calories |
|---|---|
| Sunday | — |
| Monday | — |
| Tuesday | — |
| Wednesday | — |
| Thursday | — |
| Friday | — |
| Saturday | — |
| Week total | — |
| Day | Calories |
|---|---|
| Sunday | — |
| Monday | — |
| Tuesday | — |
| Wednesday | — |
| Thursday | — |
| Friday | — |
| Saturday | — |
| Week total | — |
Check your entries
Enter your age, height, weight and activity level to estimate your daily calories.
Step 3: Set a sensible target
Once you know your maintenance calories (TDEE):
- To lose weight, eat a modest deficit — about 250–500 calories below maintenance for roughly 0.25–0.5 kg (0.5–1 lb) per week.
- To maintain, eat around your TDEE.
- To gain (muscle), eat a small surplus paired with resistance training.
Avoid extreme deficits. Crash diets cost you muscle, slow your metabolism, and rarely last. Slow and steady genuinely wins here.
Step 4: Protect your muscle with protein
When you’re in a calorie deficit, your body can burn muscle along with fat. Two things prevent that: enough protein and resistance training. Keeping muscle matters because muscle burns more energy at rest — so it keeps your BMR higher and makes maintenance easier. Use the protein calculator to set a daily target (often 1.6–2.2 g/kg when losing fat).
Step 5: Make it sustainable
The best plan is the one you can stick to. A few principles that survive contact with real life:
- Prioritise protein and fibre — they keep you full on fewer calories.
- Don’t ban foods — room for treats prevents the all-or-nothing cycle.
- Track trends, not days — weight fluctuates daily with water and food; watch the weekly average.
- Recalculate periodically — as your weight changes, so do your BMR and TDEE.
- Build habits, not deadlines — walking, sleep and consistency beat any 30-day challenge.
Putting it all together
- Check your BMI and body fat for a baseline.
- Find your TDEE to learn your maintenance calories.
- Set a modest deficit or surplus toward your goal.
- Hit a protein target and train to keep muscle.
- Adjust every few weeks and stay consistent.
No fads, no misery — just the numbers, used well.
This guide is general educational information, not medical advice. Talk to a qualified healthcare professional before starting a weight-loss or exercise program, especially if you have any health conditions.