Fat Intake Calculator

1. Weight change: \\( \Delta W = |\text{Current Weight} – \text{Goal Weight}| \\)

2. Total calories: \\( C_{\text{total}} = \Delta W \cdot 7700 \\)

3. Daily adjustment: \\( C_{\text{adjust}} = \frac{C_{\text{total}}}{\text{Weeks} \cdot 7} \\) (deficit if loss, surplus if gain)

4. BMR (Mifflin-St Jeor): \\( \text{BMR} = 10 \cdot \text{Weight} + 6.25 \cdot \text{Height} – 5 \cdot \text{Age} + 5 \\) (men) or \\( -161 \\) (women)

5. TDEE: \\( \text{TDEE} = \text{BMR} \cdot \text{Activity Multiplier} \\)

6. Total daily calories: \\( C_{\text{daily}} = \text{TDEE} \pm C_{\text{adjust}} \\) (minus for loss, plus for gain)

7. Fat intake: \\( F_{\text{daily}} = \frac{C_{\text{daily}} \cdot 0.3}{9} \\)

Where:

• \\( \Delta W \\): Weight change (kg)
• \\( C_{\text{total}} \\): Total calories for weight change (kcal)
• \\( C_{\text{adjust}} \\): Daily surplus or deficit (kcal/day)
• \\( \text{BMR} \\): Basal Metabolic Rate (kcal/day)
• \\( \text{TDEE} \\): Total Daily Energy Expenditure (kcal/day)
• \\( F_{\text{daily}} \\): Daily fat intake (g)

Assumes fat is 30% of calories, 9 kcal/g. Solves for the missing variable.

Step 1: Weight loss: \\( \Delta W = 80 – 75 = 5 \, \text{kg} \\)

Step 2: Total calories: \\( C_{\text{total}} = 5 \cdot 7700 = 38500 \, \text{kcal} \\)

Step 3: Daily deficit: \\( C_{\text{deficit}} = \frac{38500}{10 \cdot 7} \approx 550 \, \text{kcal/day} \\)

Step 4: BMR (male, 30 years, 175 cm): \\( \text{BMR} = 10 \cdot 80 + 6.25 \cdot 175 – 5 \cdot 30 + 5 \approx 1750 \, \text{kcal/day} \\)

Step 5: TDEE: \\( \text{TDEE} = 1750 \cdot 1.55 \approx 2712.5 \, \text{kcal/day} \\)

Step 6: Daily calories: \\( C_{\text{daily}} = 2712.5 – 550 \approx 2162.5 \, \text{kcal/day} \\)

Step 7: Fat intake: \\( F_{\text{daily}} = \frac{2162.5 \cdot 0.3}{9} \approx 72.08 \, \text{g/day} \\)

Result: Daily Fat Intake = 72.08 g/day.