Energy Requirement and Safe Weight-Loss Target for an Obese Sedentary Clerk
Arun, a 42-year-old bank clerk in Coimbatore, is 170 cm tall and weighs 78 kg (waist 96 cm). He sits for eight hours a day, walks fewer than 2,000 steps, and has no diagnosed illness. He wants to lose 8 kg in two months before his sister's wedding. He has begun skipping breakfast, drinking only black coffee until lunch, and eating two large helpings of rice with sambar at night. He has read that a 'low-calorie diet' means 1,000 kcal a day and that protein should be avoided at night so it 'does not turn into fat'. He eats eggs twice a week, pulses daily and chicken on Sundays, and takes no medicines. His father has type 2 diabetes. He asks whether his plan is safe and what his energy requirement actually is.
1. Calculate Arun's basal metabolic rate, total daily energy expenditure and a safe daily energy target for weight loss. State every assumption and identify which parts of his plan are unsafe.
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Step 1: classify him BMI = 78 ÷ (1.70)² = 27.0 kg/m². By Asian-Indian cut-offs (overweight 23–24.9, obese ≥25) he is obese, and a waist of 96 cm (>90 cm in men) shows central obesity. This matters because his risk of diabetes is already raised by family history.
Step 2: BMR Mifflin–St Jeor (men) = (10 × 78) + (6.25 × 170) − (5 × 42) + 5 = 780 + 1,062.5 − 210 + 5 ≈ 1,640 kcal/day. Harris–Benedict gives about 1,710 kcal; either is acceptable if the formula is stated.
Step 3: TDEE and target Sedentary factor 1.4 → 1,640 × 1.4 ≈ 2,290 kcal/day. A 500 kcal deficit gives ≈ 1,800 kcal/day, which is above his BMR and above the 1,200 kcal safety floor.
Step 4: macronutrients Protein 1.0–1.2 g/kg of ideal body weight (BMI 22 → 22 × 1.70² ≈ 64 kg) = 65–75 g. Using actual weight would over-prescribe. Fat ≈ 25% (50 g), carbohydrate ≈ 50–55% (225–245 g), fibre 25–30 g.
Unsafe elements of his plan
- 1,000 kcal is below his BMR: it costs lean mass, causes fatigue and gallstones, and predicts rebound eating.
- 8 kg in 8 weeks is 1 kg/week, the absolute upper limit; realistic fat loss is 0.5–0.8 kg/week, so 4–6 kg in two months is the honest target.
- Avoiding protein at night has no physiological basis; protein at dinner improves satiety.
2. Critique his present eating pattern and rewrite it as a day's plan of about 1,800 kcal using familiar South Indian foods. Identify the food groups each meal draws on.
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Critique
- Breakfast skipping produces hunger, poor concentration and over-eating at night; it also encourages muscle loss rather than fat loss.
- Two large rice helpings at night load about 90–110 g carbohydrate into one meal, causing a sharp post-meal glucose rise and poor sleep.
- The diet is low in vegetables, fruit, milk and good-quality protein, so 25–30 g fibre is unlikely to be met.
- Black coffee on an empty stomach worsens acidity and does not replace a meal.
Sample 1,800 kcal day
- Early morning: tea without sugar + 5 almonds (fat group).
- Breakfast: 2 idli + 1 katori sambar + 1 boiled egg or 100 g sprouted sundal (cereal + pulse + protein group).
- Mid-morning: 1 guava or apple (fruit group).
- Lunch: 1 cup rice + 1 chapati, 1 katori dal, 1 katori poriyal, 1 katori curd, salad (cereal, pulse, vegetable, milk).
- Evening: 1 glass buttermilk + 50 g sundal (milk, pulse).
- Dinner: 2 chapati + 1 katori dal or chicken (2 Sundays) + 1 katori green leafy vegetable + salad (cereal, pulse, vegetable).
Approximate totals: cereals 200–225 g, pulses 60–75 g, vegetables 400–500 g, fruit 100 g, milk/curd 300 mL, oil 15–20 g (3–4 teaspoons), free sugar nil. This delivers about 65–70 g protein and 28 g fibre.
Practical rules for him: fixed meal times, 2–3 litres water, 30-minute brisk walk five days a week, weekly weighing under the same conditions, and no 'compensation' feasts at weekends.
3. At the eight-week review, which measurements and investigations would you repeat, and why is waist circumference more informative than body weight in his case?
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Repeat measurements
- Weight and calculated BMI, measured at the same time of day.
- Waist circumference, measured midway between the lowest rib and the iliac crest at the end of normal expiration.
- Blood pressure, fasting plasma glucose or HbA1c, and a lipid profile, since central obesity with a diabetic parent puts him in a high-risk group.
- A brief adherence and hunger check: meal pattern, walking days, sleep hours and alcohol intake.
Why waist circumference matters more here Weight is a sum of fat, muscle, bone and water. A man on a crash diet can lose 3 kg of water and muscle in two weeks and look 'successful' while his visceral fat is unchanged. Waist circumference is a proxy for intra-abdominal (visceral) fat, which is the depot that drives insulin resistance, dyslipidaemia and hypertension. Two men with identical BMI can have very different waist measurements and very different metabolic risk. The target here is a waist below 90 cm, along with 5–10% weight loss; in practice his waist may fall measurably even in weeks when the weighing scale barely moves.
Judgement point If weight has fallen but waist has not, the deficit is probably too aggressive and protein intake too low; if waist is falling with stable weight, he is likely gaining muscle and losing fat. That is why both should be recorded, not weight alone.