The honest answer: somewhere between 300 and 800 calories below what you currently burn each day. That's a wide range because bodyweight, activity, age, and training history all move the number. This guide narrows it down.
Step 1: Know what you currently burn
Use the TDEE calculator. For most adults the answer lands between 1,800 and 3,200 kcal/day. Be honest about activity level, most people overestimate by one tier.
Step 2: Pick a sustainable deficit
Rule of thumb: 0.5–1% of bodyweight lost per week. Translated:
- 130 lb / 59 kg → aim for 0.5–1.0 lb/week (250–500 kcal/day deficit).
- 180 lb / 82 kg → aim for 1.0–1.5 lb/week (500–750 kcal/day deficit).
- 250 lb / 113 kg → aim for 1.5–2.5 lb/week (750–1,250 kcal/day deficit).
The bigger you start, the bigger the deficit you can run without trashing performance. The leaner you get, the smaller the deficit needs to be. The deficit calculator does this directly.
Why "1,200 calories" is usually wrong
1,200 kcal is too aggressive for most adults. It produces fast initial loss (mostly water and gut content), then crashing energy, terrible workouts, irritability, and a rebound. If your target lands below 1,500 kcal, eat more and add steps instead.
How long until I see results?
Real fat loss is visible at 4-6 weeks if the deficit is steady. The first two weeks are mostly water and food in transit. The scale lies daily, weigh every morning under identical conditions, average across the week, compare week to week.
What if I'm not losing weight?
Three possibilities in order of likelihood: (1) you're eating more than you think, track for a week with a kitchen scale, (2) you've adapted and need a small drop of 100-150 kcal, (3) you're holding water from new training or a hard week.
Sample week of meals at 1,800 kcal
Breakfast: 1 cup Greek yogurt + 1 cup berries + 30 g granola (340 kcal). Lunch: 5 oz chicken + 1 cup rice + vegetables + sauce (520 kcal). Snack: protein shake + apple (270 kcal). Dinner: 6 oz salmon + 1 cup potatoes + salad + olive oil (520 kcal). Treat: 150 kcal of whatever you want. Hits roughly 150 g protein, 60 g fat, 200 g carbs.
The bottom line
Most adults lose weight steadily eating between 1,500 and 2,500 kcal/day. Calculate your TDEE, subtract 20%, hit your protein target, and run that number for 12 weeks before reassessing.