Find your exact daily calorie target to lose weight at a healthy pace — and see when you'll reach your goal.
Your Weight Loss Plan
Suggested Daily Macros
High protein intake during a deficit helps preserve muscle mass. The macro split above uses ~35% protein, 35% carbs, 30% fat.
A calorie deficit occurs when you consume fewer calories than your body burns. It's the only scientifically proven mechanism for fat loss — regardless of which diet you follow (Hall et al., 2012).
Your body needs energy to function. When you don't provide enough through food, it taps into stored energy (primarily body fat) to make up the difference. Over time, this leads to weight loss.
One kilogram of body fat stores approximately 7,700 kcal of energy (about 3,500 kcal per pound). This gives us a practical framework:
Reality check: you won't lose only fat. Water weight fluctuates daily (sometimes by 1–2 kg), and some muscle loss is normal during a deficit — especially without adequate protein and resistance training.
Not all deficits are created equal. The right size depends on your starting point and lifestyle:
The larger the deficit, the higher the risk of muscle loss, nutrient deficiencies, and metabolic adaptation — where your body reduces its energy expenditure to compensate.
Going too aggressive with your deficit triggers a cascade of biological defence mechanisms:
Deficits compare better as a percentage of your total daily energy expenditure than as a flat kcal number. A 500 kcal cut is gentle for someone burning 3,200 kcal a day and punishing for someone burning 1,800. Three bands cover nearly everyone.
Deep cuts charge you in currencies the spreadsheet ignores. Rapid weight loss commonly triggers telogen effluvium, the diffuse hair shedding that surfaces two to three months later. Sleep gets shorter, sessions get sloppier, and the odds of quitting climb. A 30% deficit you abandon in week three loses less fat than a 15% deficit you hold for twelve.
Multiply a 500 kcal daily deficit by 365 days and the arithmetic promises 23 kg in a year. Almost nobody loses 23 kg in a year from a 500 kcal cut. The rule treats your body as a furnace of fixed output. Three things bend that line downward.
Hall (2008) modelled the whole system and offered a replacement rule: every 10 kcal/day you cut produces about 0.45 kg of eventual loss, half of it inside a year and 95% inside three. Run that on a 500 kcal cut and the first year gives about 11 kg, not 23 — the linear rule roughly doubles the twelve-month figure. Thomas et al. (2014) checked the 3,500 rule against measured trial outcomes and found the same overstatement.
Marta is 34, 168 cm and 82 kg, and trains three or four times a week. Mifflin-St Jeor puts her BMR at 1,539 kcal; at an activity multiplier of 1.55 her TDEE is about 2,385 kcal. Here is what each band asks of her.
Now the realistic column. Marta's TDEE falls as she loses, and adaptation scales with how hard she cuts, so every arm undershoots and the deepest one undershoots most. By week 12 expect something closer to 2.8 kg, 4.9 kg and 6.5 kg. In the 32% arm a larger share of that 6.5 kg is lean tissue rather than fat.
Read the last two figures together. Cutting a further 240 kcal every day for three months buys Marta about 1.6 kg, and charges her muscle, training quality and hair for it. She also has to hold 1,620 kcal for 84 days without a single lapse for the projection to hold — which is where most 30% plans actually fail. A structured deficit meal plan makes the 22% version far easier to repeat than willpower does.
This calculator won't return a target below 1,200 kcal for women or 1,500 kcal for men. The floor exists because of what has to fit underneath it. Below roughly those intakes, meeting iron, calcium and B12 targets from food alone gets difficult, and protein starts crowding everything else off the plate.
Do the arithmetic. Helms et al. (2014) recommend 1.6–2.4 g of protein per kg of body weight for people dieting while lifting. For a 60 kg woman that's 96–144 g, or 384–576 kcal, before a single vegetable, and fat still needs its share for hormone production. On 1,200 kcal the remaining budget is tight enough that every choice has to earn its place. Our guide to daily protein needs covers how to distribute it.
The US National Institutes of Health classifies anything under 800 kcal/day as a very-low-calorie diet and says it belongs under medical supervision. If the calculator caps your result at the floor, choose a gentler pace or add daily movement rather than hunting a smaller number. Anyone pregnant or breastfeeding, managing a diagnosed condition, taking a prescribed weight-loss medication, or with any history of disordered eating should set intake with a dietitian or doctor instead of a web form — this one included. See whether 1,200 calories is enough for the longer version.
A 500 kcal deficit burns roughly 70 g of fat a day. Ordinary day-to-day weight swings run ten to twenty times larger, so on any single morning noise buries that signal. What's actually moving the number:
Read the trend instead. Weigh every morning after the toilet and before food, then compare this week's 7-day average with last week's. Zheng et al. (2015) reviewed daily self-weighing and found it associated with greater weight loss and no worsening of mood. Three flat weekly averages in a row is a signal worth acting on; one heavy Tuesday is not. Water weight explains most of the noise, and a genuine plateau looks different from a bad week.
A diet break means eating at maintenance — your current TDEE, not the one you started with — for one or two weeks, then returning to the deficit. It's a scheduling decision, not a reward.
Byrne et al. (2018), the MATADOR trial, ran men with obesity through either 16 continuous weeks at a 33% deficit or 30 weeks alternating two weeks of deficit with two weeks at maintenance. Both groups spent 16 weeks in deficit. The intermittent group lost more fat and showed a smaller drop in resting energy expenditure. Peos et al. (2021) repeated the design with lean, resistance-trained people and found no reliable fat-loss advantage, so treat the metabolic benefit as unsettled and take the break for adherence.
Reasonable triggers: eight to twelve unbroken weeks in a deficit, a 7-day average that hasn't moved in three weeks despite honest logging, training numbers sliding backwards, or a holiday you'd rather enjoy than survive. Expect the scale to jump 1–2 kg in the first few days as glycogen and its water return. That isn't fat. When the break becomes the destination rather than a pause, reverse dieting covers how to raise calories deliberately.
How big should my calorie deficit be?
Most people do well at 20–25% below TDEE, which works out to roughly 0.5–0.75% of body weight per week. Drop to 10–15% if you're within a few kilos of goal or training hard. Treat anything past 30% as a short-term tool rather than a plan you can hold.
Is a 500-calorie deficit enough to lose weight?
It depends entirely on your TDEE. At 2,400 kcal, a 500 kcal cut is a 21% deficit and gives about 0.45 kg per week. At 1,700 kcal the same 500 kcal is a 29% deficit and pushes you close to the calorie floor. Judge the deficit as a share of your own maintenance, never as a flat number.
How long before I see results from a calorie deficit?
The first week often shows 1–3 kg of water and glycogen, which flatters the start and then stops. Genuine fat loss becomes readable on a 7-day average around week three or four. Clothes and photographs usually register the change before the mirror does.
Why am I in a calorie deficit and not losing weight?
Three causes cover most cases: underlogging (cooking oil, weekends, drinks), a TDEE that has fallen since you set the target, and water masking real loss. Compare 7-day averages across three weeks before changing anything. If it's genuinely flat, weigh your food for a fortnight before cutting calories again.
Can I eat 1,200 calories a day to lose faster?
For most women 1,200 kcal is a floor rather than a target, and for most men it sits below the floor entirely. Fitting 100 g of protein, 25 g of fibre and a full micronutrient profile into 1,200 kcal takes real planning. Anything lower belongs with a doctor or dietitian, not a calculator.
Should I eat back the calories I burn from exercise?
Not if the activity level you picked already includes your training — you'd be counting it twice. The multiplier in this calculator covers habitual exercise. MacroLog reads steps and active energy from Apple Health and Health Connect for display only, and deliberately never adds them to your daily calorie budget.
How often should I recalculate my deficit?
Every 4–5 kg lost, or every eight weeks, whichever arrives first. Your TDEE falls as you get lighter, so a target set at 90 kg has quietly stopped being a deficit by the time you reach 82 kg.
Do I need a diet break?
Nobody needs one, but they help after eight to twelve unbroken weeks in a deficit or whenever adherence starts slipping. Two weeks at maintenance rarely costs more than a week of progress and often buys several more months of consistency.