BMR, TDEE and exact calorie targets for weight loss, maintenance and muscle gain at age 21.
Using the Mifflin-St Jeor equation with average US height and weight for a man aged 21, the resting metabolic rate (BMR) is approximately 1884 kcal/day. With typical daily activity included, total calorie expenditure (TDEE) ranges from 2260 kcal (sedentary) to 3249 kcal (very active).
| Goal | Daily Calories | Expected Result |
|---|---|---|
| 🔵 Aggressive weight loss | 1840 kcal | ~0.75 kg/week |
| 📉 Weight loss | 2090 kcal | ~0.5 kg/week |
| ✅ Maintenance | 2590 kcal | Weight stable |
| 💪 Lean bulk | 2890 kcal | ~0.25 kg/week |
| 🏋️ Aggressive bulk | 3090 kcal | ~0.5 kg/week |
| Activity Level | Description | Daily Calories |
|---|---|---|
| Sedentary | Desk job, minimal movement | 2260 kcal |
| Lightly active | 1–3 workouts/week | 2590 kcal |
| Moderately active | 3–5 workouts/week | 2920 kcal |
| Very active | Hard training 6–7 days/week | 3249 kcal |
Metabolic rate declines approximately 1–2% per decade after age 30, driven primarily by muscle loss (sarcopenia) rather than any inherent slowdown. At age 21, your BMR of 1884 kcal reflects your current muscle mass, height and hormonal status. The single most effective way to maintain or raise your BMR is resistance training — each kilogram of lean muscle burns roughly 13 kcal/day at rest.
| Age | Estimated BMR (man) | Change vs age 21 |
|---|---|---|
| 18 | 1899 kcal | +15 kcal |
| 18 | 1899 kcal | +15 kcal |
| 21 | 1884 kcal | — |
| 26 | 1859 kcal | -25 kcal |
| 31 | 1834 kcal | -50 kcal |
| Macro | % of Calories | Grams/day | Calories |
|---|---|---|---|
| Protein | 30% | 194 g | 776 kcal |
| Carbohydrates | 40% | 259 g | 1036 kcal |
| Fat | 30% | 86 g | 774 kcal |
At age 21, protein intake is especially important. Aim for at least 71–89 g/day to maintain muscle mass, whether you're in a deficit, at maintenance, or in a surplus.
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