Combien de Calories Manger pour Perdre du Poids ?

How Many Calories Do You Need to Lose Weight?

Weight loss comes down to energy balance: consume fewer calories than you burn, and your body draws on stored fat. The math is straightforward, but your personal number depends on your total daily energy expenditure (TDEE) — the calories you burn across everything from basic organ function to exercise.

A 500 calorie/day deficit equals roughly 1 pound per week of fat loss. A 250 calorie/day deficit equals about half a pound per week. These aren’t estimates — they come directly from the fact that one pound of body fat contains approximately 3,500 calories.

Use the calorie calculator to find your TDEE and target intake automatically.

Step 1: Calculate Your TDEE

TDEE starts with your Basal Metabolic Rate (BMR) — calories your body burns at rest — then multiplies by an activity factor.

The Mifflin-St Jeor equation is the most validated BMR formula for most adults:

Men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5

Women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161

Then multiply by your activity level:

Activity Level	Description	Multiplier
Sedentary	Desk job, little or no exercise	1.2
Lightly active	Light exercise 1-3 days/week	1.375
Moderately active	Moderate exercise 3-5 days/week	1.55
Very active	Hard exercise 6-7 days/week	1.725
Extremely active	Physical job + hard daily exercise	1.9

Step 2: Set Your Calorie Target

Subtract 500 from your TDEE for 1 lb/week loss. Subtract 250 for 0.5 lb/week. Never go below the minimum floors (see below).

Example: 35-year-old woman, 165 lbs (75 kg), 5’6” (168 cm), moderately active.

• BMR = (10 x 75) + (6.25 x 168) - (5 x 35) - 161 = 750 + 1,050 - 175 - 161 = 1,464 calories
• TDEE = 1,464 x 1.55 = 2,269 calories
• Target for 1 lb/week loss: 2,269 - 500 = 1,769 calories/day

Calorie Targets by Body Weight and Activity Level

These are approximate 500 cal/day deficit targets for weight loss (1 lb/week). Assumes average height and age 35.

Women (5’5”, age 35):

Body Weight	Sedentary	Lightly Active	Moderately Active	Very Active
140 lbs	1,240	1,450	1,660	1,880
160 lbs	1,320	1,540	1,760	1,990
180 lbs	1,400	1,640	1,870	2,120
200 lbs	1,480	1,730	1,980	2,240
220 lbs	1,560	1,820	2,090	2,360

Men (5’10”, age 35):

Body Weight	Sedentary	Lightly Active	Moderately Active	Very Active
160 lbs	1,450	1,700	1,950	2,200
180 lbs	1,530	1,790	2,060	2,320
200 lbs	1,620	1,890	2,170	2,450
220 lbs	1,710	1,990	2,280	2,580
240 lbs	1,790	2,090	2,400	2,710

Minimum Calorie Floors

Going too low backfires. Below certain thresholds, the body reduces thyroid output, drops non-exercise movement (fidgeting, posture changes), and breaks down muscle for fuel.

• Women: 1,200 calories/day minimum
• Men: 1,500 calories/day minimum

If your calculated deficit target falls below these numbers, aim for the floor instead. You’ll lose weight more slowly, but you’ll preserve muscle, maintain energy, and avoid the metabolic slowdown that makes rebounding so common.

Very low calorie diets (800 calories or fewer) require medical supervision. They produce faster short-term loss but carry risks: gallstone formation, nutrient deficiencies, cardiac stress, and higher rates of weight regain.

Activity Level Has a Large Impact

The difference between sedentary and very active TDEE is often 600-900 calories per day. A 180-pound woman who exercises 6 days a week can eat 600 more calories daily than her sedentary counterpart and lose weight at the same rate. This is why adding exercise gives you more room to eat while still in a deficit.

However, exercise also increases appetite. Studies show that for most people, exercise contributes to weight loss primarily through calorie burn rather than appetite suppression. Don’t assume you can eat back 100% of exercise calories — calorie tracking apps often overestimate burn by 20-30%.

Why Plateaus Happen (and What to Do)

If you lose 20 pounds, you’re carrying 20 fewer pounds all day. Your BMR drops. Your TDEE drops. The same calorie intake that created a 500 cal/day deficit three months ago may now only create a 200 cal/day deficit.

Recalculate your TDEE every 10-15 pounds lost. Adjust your calorie target accordingly. This is the single most common reason “nothing works” after initial success.

Other plateau causes:

• Inaccurate calorie tracking (restaurant meals, cooking oils, handfuls of nuts)
• Water retention from high sodium, menstrual cycle, or new strength training
• Metabolic adaptation — real but usually 100-200 calories, not 500+

A 1-2 week diet break at maintenance calories can reset leptin levels and ease adaptive thermogenesis before continuing a deficit.

Macro Split for Fat Loss

Calories determine whether you lose weight. Macros determine what you lose (fat vs. muscle).

Recommended split for fat loss:

Macro	Target	Why
Protein	0.7-1.0g per lb body weight	Preserves muscle, high satiety, high thermic effect
Fat	0.35-0.5g per lb body weight	Hormonal health, fat-soluble vitamins
Carbohydrates	Remaining calories	Fuels training, glycogen stores

Example (1,750 cal target, 160 lb person):

• Protein: 160g x 4 cal = 640 calories
• Fat: 65g x 9 cal = 585 calories
• Carbs: (1,750 - 640 - 585) / 4 = 131g

Higher protein intakes during a deficit consistently outperform lower protein intakes for body composition. A 2020 meta-analysis in the Journal of the Academy of Nutrition and Dietetics found that protein intakes above 1.2g/kg of body weight significantly reduced lean mass loss during calorie restriction.

Tracking Your Intake

Self-reported food intake is notoriously inaccurate. Studies show people underreport calorie intake by an average of 12-20%. Common errors:

• Not measuring oils, butter, or sauces (1 tablespoon of olive oil = 120 calories)
• Estimating portion sizes vs. weighing them
• Not tracking “small” items (coffee creamer, condiments, tasting while cooking)

A food scale eliminates most tracking errors. Weigh food raw when possible, since cooking changes weight. You don’t need to weigh forever — most people develop accurate portion estimation after 4-8 weeks of tracking.

Putting It Together

1. Calculate your TDEE using the formula or calorie calculator
2. Subtract 250-500 calories for a sustainable deficit
3. Set protein first (0.7-1.0g per lb), fill remaining calories with fat and carbs
4. Track intake accurately for at least the first 4 weeks
5. Recalculate TDEE every 10-15 lbs lost
6. Expect a 0.5-1.5% body weight loss per week as sustainable progress

Weight loss isn’t linear. A week with no scale movement doesn’t mean the deficit isn’t working — water retention, muscle glycogen, and digestive content fluctuate by 2-4 pounds day to day. Judge progress over 3-4 week averages.

How Long Will It Take?

With a 500 cal/day deficit producing ~1 lb/week loss, here’s a realistic timeline based on starting body fat percentage and goal:

Goal	Starting Weight	Loss Needed	Time at 1 lb/week
Lose 10 lbs	170 lbs	10 lbs	10-12 weeks
Lose 20 lbs	190 lbs	20 lbs	20-26 weeks
Lose 30 lbs	210 lbs	30 lbs	30-40 weeks
Lose 50 lbs	230 lbs	50 lbs	50-65 weeks

Add 20-30% to these timelines to account for natural plateaus, diet breaks, and the fact that rate of loss typically slows as you approach your goal weight. Losing the last 10 lbs is always harder than losing the first 10, because your TDEE is lower and the gap between maintenance and deficit narrows.

TL;DR

• 500-calorie deficit = 1 lb/week: One pound of fat contains ~3,500 calories — a consistent 500 cal/day deficit produces about 1 lb of fat loss per week, or 0.5 lb/week at a 250 cal/day deficit.
• Calorie floors: Never go below 1,200 calories/day for women or 1,500/day for men — dropping below these levels risks muscle loss, metabolic slowdown, and nutrient deficiencies.
• Recalculate every 10-15 lbs: Losing 20 lbs means your TDEE drops — the same intake that created a 500 cal deficit earlier may now only create a 200 cal deficit, which is why plateaus happen.
• Protein target: Eat 0.7-1.0g of protein per pound of body weight during a deficit to preserve muscle mass and stay satiated — inadequate protein means losing muscle alongside fat.
• Track accurately: People underreport calorie intake by 12-20% on average — weigh food raw with a scale for the first 4-8 weeks to calibrate your portion estimation before relying on estimation.