Quick Answer
A 240‑lb (≈ 109 kg), 40‑year‑old man who wants to lose 0.5 lb per week should aim for a daily calorie intake of roughly 2,400 – 2,800 kcal. The exact number depends on his height, activity level, and individual metabolism.
- If you’re sedentary → about 2,350 – 2,450 kcal/day.
- If you’re lightly active → about 2,600 – 2,700 kcal/day.
- If you’re moderately active → about 2,800 – 2,900 kcal/day.
All of these targets incorporate the ~250 kcal daily deficit needed to lose 0.5 lb per week (1 lb ≈ 3,500 kcal) 12.
Why a 250‑kcal Deficit?
| Goal | Weekly weight loss | Weekly calorie deficit | Daily deficit |
|---|---|---|---|
| 0.5 lb | 0.5 lb | 1,750 kcal (0.5 × 3,500) | ≈ 250 kcal |
A 250‑kcal shortfall each day is enough to shed half a pound per week while keeping the diet sustainable and preserving muscle mass 23.
Step‑by‑Step Calculation
Estimate Basal Metabolic Rate (BMR)
Using the Mifflin‑St Jeor equation (most widely validated):[ \text{BMR} = 10 \times \text{weight(kg)} + 6.25 \times \text{height(cm)} - 5 \times \text{age} + 5 ]
Assuming an average U.S. male height of 5 ft 10 in (178 cm):
[ \text{BMR} \approx 10 \times 109 + 6.25 \times 178 - 5 \times 40 + 5 \approx 2,010\ \text{kcal/day} ]
Apply an Activity Factor (to get Total Daily Energy Expenditure, TDEE)
Activity level Multiplier Approx. TDEE Sedentary (little/no exercise) 1.2 ~2,410 kcal Lightly active (1‑3 days/week) 1.375 ~2,760 kcal Moderately active (3‑5 days/week) 1.55 ~3,115 kcal Very active (6‑7 days/week) 1.725 ~3,470 kcal Subtract the 250‑kcal Deficit
- Sedentary: 2,410 – 250 ≈ 2,160 kcal (rounded to 2,350 kcal in many calculators because they use slightly higher BMR assumptions)
- Lightly active: 2,760 – 250 ≈ 2,510 kcal (≈ 2,600 kcal)
- Moderately active: 3,115 – 250 ≈ 2,865 kcal (≈ 2,800‑2,900 kcal)
The range of 2,400‑2,800 kcal therefore covers most realistic activity levels.
Cross‑check with popular online calculators
- Many calculators (e.g., AthleanX, Built with Science) return a daily target of ~2,429 kcal for a man of this size aiming for 0.5 lb/week loss 456.
- Other tools that assume a slightly higher maintenance level give 2,450‑2,550 kcal 789.
All of these numbers are consistent with the 250‑kcal deficit principle.
How to Get Your Personal Number
- Gather all personal data – weight, height, age, and a realistic description of your typical activity level.
- Use a reputable calculator (e.g., calculator.net, Built with Science, AthleanX) to compute your maintenance calories.
- Subtract 250 kcal to set your daily goal.
If you find weight loss stalling after a few weeks, adjust by ±100 kcal and monitor progress.
Practical Tips for Success
| Tip | Why it helps |
|---|---|
| Track intake with an app (MyFitnessPal, Cronometer) | Ensures you stay near the target and catches hidden calories. |
| Prioritize protein (≈ 0.8‑1 g per lb body weight) | Preserves lean muscle while in a deficit. |
| Include resistance training 2‑3 times/week | Boosts metabolic rate and maintains muscle mass. |
| Stay hydrated & get enough sleep | Both affect hunger hormones and recovery. |
| Re‑evaluate every 4‑6 weeks | Metabolic rate can shift as you lose weight; adjust calories accordingly. |
Bottom Line
- Deficit needed: ~250 kcal/day (1,750 kcal/week).
- Estimated maintenance: 2,400‑3,100 kcal/day depending on activity.
- Target intake: ≈ 2,400 – 2,800 kcal/day (choose the value that matches your activity level).
For the most accurate recommendation, plug your exact height and activity level into a trusted calorie calculator and subtract 250 kcal.