Fat loss
Calorie Deficit: How Much to Eat to Lose Weight (With Charts)
Published October 20, 2026
A calorie deficit means eating fewer calories than your body burns, which forces it to draw on stored energy, mostly fat. For most adults, a deficit of about 300 to 500 calories a day is a sustainable starting point. Weight loss then slows over time as your body gets smaller, so expect to adjust, not to lose in a straight line.
Every diet that works, from keto to intermittent fasting, works by creating a calorie deficit. The details (what you eat, when) matter for hunger, health and muscle, but energy balance is the engine. Here is how to set yours and what to expect, using numbers from research rather than from the old "3,500 calories = 1 lb" rule.
Step 1: Estimate your maintenance calories
Maintenance is what you burn in a day: resting metabolism plus digestion plus all movement. Two ways to find it:
Quick estimate (rule of thumb)
| Activity level | Calories per lb of body weight | Calories per kg |
|---|---|---|
| Mostly sitting, little exercise | 12-13 | 26-29 |
| Light activity, 2-3 workouts/week | 14-15 | 31-33 |
| Active job or 4-5 workouts/week | 16-17 | 35-37 |
| Very active (manual work + training) | 18+ | 40+ |
Example: a 170 lb (77 kg) person with 3 workouts a week ≈ 170 x 14.5 ≈ 2,450 calories.
Accurate method (recommended)
Log what you eat for 2 weeks and weigh yourself each morning. If your weekly average is stable, your average intake is your maintenance. This beats any calculator because it measures you.
Step 2: Choose the size of the deficit
| Deficit per day | Typical early pace | Good for |
|---|---|---|
| 250-300 kcal | Slow | Lean people, lifters protecting muscle |
| 400-500 kcal | Moderate | Most people |
| 600-750 kcal | Faster | Higher body fat, short phases, ideally with guidance |
| 1,000+ kcal | Aggressive | Medical supervision only |
Very low intakes (under about 1,200 kcal for women or 1,500 kcal for men) make it hard to get enough protein and nutrients and should be supervised by a professional.
Why the "3,500-calorie rule" disappoints people
The old rule says cutting 500 calories a day loses 1 lb (0.45 kg) a week forever. In reality, as you lose weight you burn less, so the same deficit produces slower loss over time. Kevin Hall and colleagues modeled this in The Lancet in 2011. Their rule of thumb for adults: every 10 calories per day of sustained change leads to about 1 lb (0.45 kg) of eventual weight change, with about half of it reached in roughly a year and most of it in about three years.
So a sustained 250 calorie cut means about 25 lb (11 kg) eventually, but not in 25 weeks. Losses are fastest early and then taper. That's normal physics, not a broken metabolism.
Step 3: Protect muscle and hunger
A deficit can remove muscle as well as fat. To push the loss toward fat:
- Protein: 0.7 to 1 g per lb (1.6 to 2.2 g/kg) per day. Chart: how much protein per day.
- Strength training 2 to 4 times a week. Even beginners keep or gain muscle with a beginner workout plan.
- Daily walking. More steps raise your expenditure with little hunger or fatigue: walking for weight loss.
- Fiber and volume: vegetables, fruit, legumes, potatoes, soups.
- Sleep 7 to 9 hours. Short sleep raises appetite.
Step 4: Track and adjust
- Weigh daily, look at the weekly average.
- Measure your waist every two weeks.
- If the weekly average hasn't moved for 2 to 3 weeks (and you've been consistent), reduce intake by 100 to 200 calories or add 2,000 to 3,000 steps a day.
- Women: compare the same week of your cycle, since water retention varies.
Sample day at ~1,800 kcal (for a 170 lb / 77 kg person losing at a moderate pace)
| Meal | Food | Approx. kcal | Protein |
|---|---|---|---|
| Breakfast | Greek yogurt (1 cup), berries, 2 tbsp granola | 300 | 25 g |
| Lunch | Chicken (5 oz / 140 g), quinoa (1 cup), big salad, olive oil (1 tsp) | 550 | 45 g |
| Snack | Apple + string cheese | 180 | 7 g |
| Dinner | Salmon (5 oz / 140 g), potatoes (7 oz / 200 g), vegetables | 600 | 35 g |
| Evening | Cottage cheese (1/2 cup) | 110 | 13 g |
| Total | ≈1,740 | ≈125 g |
Signs your deficit is too big
- Constant hunger, irritability, poor sleep.
- Training performance dropping fast.
- Dizziness, hair shedding, or (for women) changes in the menstrual cycle.
Ease off and talk to a doctor if symptoms persist.
Who should not diet without medical advice
Pregnant or breastfeeding women, teenagers, people with a history of eating disorders, people with diabetes on medication, or anyone with a chronic condition.
Keep going
For belly fat specifically, read how to lose belly fat. For lifters, cutting diet covers macros and lifting during a deficit. If you'd like a structured 12-week training plan to go with your deficit, our programme has home and gym tracks.
Frequently asked questions
How do I know if I'm in a calorie deficit?
The most reliable sign is a downward trend in your weekly average body weight over 2 to 3 weeks. Day-to-day weight jumps around by 1 to 3 lb (0.5 to 1.5 kg) because of water, salt and food volume, so single weigh-ins can mislead. If the trend is flat, you're at maintenance, whatever an app says.
Why am I not losing weight in a calorie deficit?
Most often, the deficit is smaller than you think: portions are underestimated, weekends undo weekday efforts, or drinks and snacks aren't counted. Water retention can also hide fat loss for a week or two, particularly when starting a new exercise program or around the menstrual cycle. Track carefully for two weeks before changing anything.
Can I eat junk food in a calorie deficit?
Technically you can lose weight eating anything as long as total calories are lower than you burn. In practice, highly processed foods are less filling, so the deficit becomes harder to sustain, and you risk missing protein, fiber and micronutrients. A flexible approach (mostly whole foods, some treats) works best for most people.
Is a 1,000-calorie deficit safe?
For some people with a lot of weight to lose, a larger deficit can be appropriate for a limited time, ideally with medical supervision. For most, it leads to strong hunger, fatigue, muscle loss and rebound eating. Starting at 300 to 500 calories and adjusting is more sustainable.
Does a calorie deficit slow metabolism?
Your energy expenditure decreases as you lose weight, mostly because a smaller body burns less and you may move less without noticing. There is also some adaptive reduction. It doesn't stop fat loss, but it's why you need to adjust intake or activity over time, and why the 3,500-calorie rule overpredicts long-term loss.
Should I eat back the calories I burn exercising?
Fitness trackers often overestimate exercise calories. A safer approach: set your intake based on your scale trend, not on daily tracker numbers. If you're losing much faster than planned or feel exhausted, eat a little more on training days.
Studies cited
- Hall KD et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet. doi:10.1016/S0140-6736(11)60812-X
- Helms ER, Aragon AA, Fitschen PJ (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition. doi:10.1186/1550-2783-11-20