16:8 vs OMAD: Weight-Loss Calculator
Which loses weight faster, and by how much? The tool loads 16:8 — run it for your body, then switch the schedule to OMAD to see both projections side by side.
Intermittent Fasting Calculator
Pick the eating pattern you’ll actually follow. We estimate the calorie reduction it typically produces — you can fine-tune it below.
Used to estimate your maintenance calories with the Mifflin-St Jeor equation, and to set a safe minimum-intake floor.
Range: 15–100 years
Range: 30–300 kg
Enter your height in centimeters (e.g., 170 cm)
Range: 100–250 cm
Add a target and we’ll estimate how many weeks the schedule takes to get there.
Know roughly what you eat on a fasting day? Enter it for a precise projection. Leave blank and we’ll estimate the typical reduction for this schedule. Not sure? Get a calorie target free.
Already know your maintenance (TDEE)? Enter it to skip the estimate — height and age aren’t needed then. Don’t know it? Work it out free.
*This calculator is for informational purposes only. Please consult a healthcare professional before making any health decisions. See our medical disclaimer for more information.
Quick Answer
16:8 vs OMAD — The Short Answer
For a lightly active woman near 75 kg (maintenance about 1,990 kcal), 16:8 projects about 0.36 kg (0.8 lb) a week and OMAD about 0.63 kg (1.4 lb) — roughly double, because OMAD cuts intake by 30–40% against 15–25% for 16:8. But faster isn't automatically the pick. The calculator above is loaded with 16:8; run it for your body, then switch the dropdown to OMAD to see both numbers side by side.
The Short Answer
The difference between 16:8 and OMAD comes down to how much they cut your intake. A 16:8 window trims a typical eater by around 15–25%; OMAD, with a single daily meal, pushes that to 30–40%. For the worked body — maintenance about 1,990 calories — 16:8 lands intake near 1,590 for a deficit around 400, projecting about 0.36 kg a week, while OMAD lands intake near 1,290 for a deficit close to 700, projecting about 0.63 kg. That is roughly twice the weekly loss on paper. It is a real difference, and it is exactly the sort of comparison the calculator makes concrete for your own body when you run one schedule and then the other.
Why Faster Isn't Automatically the Pick
Double the weekly loss sounds like an easy choice until you look at the costs. OMAD's estimated intake of around 1,290 calories sits close to the 1,200-calorie floor the tool flags for women, and for a lighter person it dips below — the point at which cutting further stops being wise without supervision. A deficit that size is also more likely to take muscle along with fat, and squeezing a full day of protein and nutrients into one meal is genuinely hard. On top of that, controlled trials find that once total calories are matched, fasting schedules produce about the same result regardless of the clock (Liu et al., NEJM 2022). So the extra speed of OMAD only pays off if you can hold it — and many people can hold 16:8 for far longer.
See It for Your Body — and a Middle Path
Numbers on a page are less persuasive than numbers on your own body. The calculator above is set to 16:8: enter your weight, height, age, gender and activity, read the projected loss, then switch the schedule dropdown to OMAD and watch the deficit and weekly figure change. Seeing both for your maintenance makes the trade-off concrete. And the choice isn't only these two extremes — an 18:6 or 20:4 window sits between them, keeping much of OMAD's deficit with two meals to work with, which is often the sweet spot. Confirm the maintenance the whole comparison rests on with the TDEE Calculator, or plan a steady daily deficit with the Calorie Deficit Calculator.
Maintenance uses Mifflin-St Jeor; the safe-minimum floors (1,200 kcal women / 1,500 kcal men) follow NHS lower limits for unsupervised dieting. Figures are general guidance, not medical advice (Liu 2022). Anyone pregnant, under 18, diabetic, or with a history of disordered eating should speak to a clinician before fasting.
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