Reverse Dieting Calculator — Free

When you spend weeks or months in a calorie deficit, your body defends itself against further weight loss by lowering its energy expenditure — a phenomenon researchers call adaptive thermogenesis, or metabolic adaptation (Trexler, Smith-Ryan & Norton, 2014). Beyond the calories you no longer burn simply because you weigh less, your total daily energy expenditure can fall by a further 5–15%. Three things drive it:

• Leptin falls. This is the hormone that signals energy availability; as fat stores and food intake drop, so does leptin, which down-regulates metabolic rate and ramps up hunger.
• Thyroid output drops. Active thyroid hormone (T3) declines during restriction, lowering resting energy use.
• Hunger and NEAT shift. Ghrelin (the hunger hormone) rises, while non-exercise activity — fidgeting, walking, general movement — quietly decreases, burning fewer calories. These hormonal shifts can persist for a year or more after weight loss (Sumithran et al., 2011).

Snapping straight back to your old intake floods this suppressed system with energy it is not yet ready to expend, which is why rapid post-diet fat regain is so common. Reverse dieting works with the physiology: a slow, steady rise in calories gives leptin, thyroid output, and spontaneous movement time to recover, so your maintenance level drifts back up as you eat more.

An honest note on the evidence: metabolic adaptation itself is well documented — it persisted six years after extreme weight loss in the “Biggest Loser” follow-up (Fothergill et al., 2016) — but reverse dieting as a specific protocol has not yet been tested in large controlled trials. It is a sensible, low-risk way to apply that physiology — not a guaranteed metabolic “reset.” Treat the plan as a structured starting point and let your own weekly weigh-ins drive the pace.

1. Enter your current calories. Be honest about what you actually eat now, at the end of your diet — this is the floor your plan ramps up from.
2. Add your stats. Weight, height, age, gender and activity let the calculator estimate your maintenance with the Mifflin-St Jeor equation. Already know your maintenance? Type it into the optional field and skip the estimate.
3. Pick a pace. Conservative (+50/week), moderate (+100/week) or aggressive (+150/week) — or set a custom rate.
4. Set protein and (optionally) weeks dieting. Protein is held flat to protect muscle; weeks dieting sharpens the rebound-risk read.
5. Read your plan. You get your maintenance target, total weeks, a week-by-week calorie and macro schedule, and a rebound-risk rating with a recommendation.

Not sure of your maintenance number? Confirm it across three formulas with the TDEE Calculator, then come back. Planning a future cut instead? Use the Calorie Deficit Calculator. Finishing a specific diet? We have ramps pre-set for reverse dieting from 1,200 calories, and if you just want the weekly number, see how many calories to add each week.

The schedule is a starting plan, not a contract — your own weekly weigh-ins decide the pace. Track a morning weight a few times a week and watch the trend, not any single day:

• Gaining under ~0.5% of bodyweight per week? You are on track — add the next increment as scheduled.
• Weight stable for two weeks? You can move a little faster — your metabolism is keeping up with the extra food.
• Gaining faster than expected? Hold the current calories an extra week before the next increase, and check that your protein and step count haven't slipped.

Keep protein high and resistance training in place throughout — that is what biases the small surplus toward muscle rather than fat. A meta-analysis of protein and resistance training found gains plateau at about 1.6 g of protein per kg of bodyweight per day (Morton et al., 2018), which is the floor this calculator uses. Re-split any week's calories with the Macro Calculator.