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Farhan is 34, writes software in Hyderabad, and weighs 88 kilos at 175 cm. Last month he typed his details into a calorie app, which told him to eat 1,700 a day. He tried it for a week and was starving by four every afternoon. His teammate Vikram used the same app, lost seven kilos by August and has been stuck ever since. This page works through both of their problems. Farhan and Vikram are composites of the readers who ask this, not real patients.
A calorie deficit means eating less energy than your body uses, so it draws on stored fat. For most adults a daily gap of between 300 and 500 calories is enough to lose weight steadily without constant hunger. The gap shrinks as you get lighter, so the plan needs adjusting every few months.
What is a calorie deficit, in plain terms?
Your body burns energy all day to keep you alive, to digest food and to move. If you eat less than that total, the shortfall is taken from stored fat, along with a little muscle and water. That shortfall is the deficit.
For Farhan it helps to picture his day. He sits at a desk from ten to seven, takes the cab both ways, and plays badminton on Saturdays. His body might burn something around 2,300 calories on a weekday. If he eats 1,900, the missing 400 come out of storage. No food has to be banned for that to happen, which is the good news. The harder part is that the gap has to stay open on most days, for months, including the day of his cousin's nikah.
You may have read that 7,700 calories equals a kilo of fat, so a 500-calorie gap loses half a kilo a week. Kevin Hall's modelling at the US National Institutes of Health shows that rule holds only for the first few weeks. After that the body's needs fall and the same gap produces less, which is why Farhan should judge his plan by the trend over a month rather than by the arithmetic.
Sources: [1]
How do you estimate how many calories you burn?
Every calculator gives a guess, and for one person the guess can be off by a few hundred calories. Farhan's app used his height, weight, age and the "lightly active" box he ticked. Herman Pontzer's large study of measured energy use found that, once body size is accounted for, daily expenditure holds steady between about 20 and 60 and falls after that. So turning 30 has not slowed him down.
His step count has. On weekdays he walks about 3,000 steps, from the cab to his desk and back, which is closer to "sedentary" than to the box he ticked. The way to find his real number is to eat at the app's level for three weeks and average his weight across each week. If the average has not dropped by then, his true burn is lower than the estimate. He trims another 200 calories, or adds a 30-minute walk after dinner along the lake near his flat.
Sources: [2]
How big should the deficit be?
For most people, somewhere between 300 and 500 calories a day. Bigger gaps lose weight faster at first, but Steven Heymsfield's analysis of diet trials shows that a larger share of the loss comes from lean tissue when cuts are steep and protein is low.
Farhan's app suggests 1,700, which is a deficit of around 600 on his estimated burn. He could live on that, but his badminton would suffer and his evenings would be ruled by hunger. We would start him nearer 1,900 or 2,000 and keep protein high. On paper he loses a little more slowly. In practice he is far more likely to still be at it in March, when the steep version would long since have ended in a weekend of pizza.
Sources: [7]
What does a 1,900-calorie Indian day look like?
Farhan's Tuesday, as we would plan it, starts at 8.30 with a bhurji of one whole egg and three whites, a phulka and tea with half a spoon of sugar. At 1.30 the office canteen has dal, aloo gobhi, salad and rotis; he takes two rotis, a big helping of the dal and leaves the pakoras on the counter. At five, when the team orders samosas, he eats the curd and banana he brought from home.
Dinner is chicken curry his flatmate makes with one spoon of oil, a bowl of cucumber raita and a small katori of rice. That day comes to about 1,900 calories and roughly 110 grams of protein. Heather Leidy's review of feeding trials found that meals higher in protein leave people fuller and eating less later, which is why the eggs at breakfast make the samosa easier to skip. On Friday he has one plate of biryani with raita and no cold drink, and the week still balances.
Sources: [6]
Why does the deficit shrink after a few months?
Because a lighter body burns less, and Vikram is the example. He went from 91 kilos down to 84 between May and August on 1,800 calories a day, then stalled for two months. At 84 kilos his body runs on less energy than it did at 91, so the 500-calorie gap he began with has shrunk to perhaps 200.
Kevin Hall's model at the US National Institutes of Health predicts that slowing on any fixed intake. Michael Rosenbaum and Rudolph Leibel's work adds that after weight loss, energy use falls a little further than the smaller body alone explains. Vikram's next step is small: drop the second roti at dinner, or walk briskly for half an hour on weekday evenings. Crashing to 1,200 calories would cost him muscle and usually ends in a weekend binge.
Why does hunger get stronger the longer you diet?
Appetite rises as weight falls, and it rises faster than energy use drops. Corby Polidori and colleagues estimated that people eat about 100 calories a day more for every kilo lost. After eight kilos, Farhan is pushing back against a pull of several hundred extra calories a day that he did not feel in week one.
Knowing that turns the late-night hunger into something expected instead of a personal failing. Practical counterweights help. Protein at every meal, a big salad before dinner, seven hours of sleep, and a planned evening snack of curd or roasted chana all take the edge off. Farhan also keeps chips out of the flat. If they are in the cupboard at 11 pm, they will be eaten.
Sources: [4]
How do you stay in a deficit without losing muscle?
Eat plenty of protein and lift weights. Thomas Longland's trial put young men on a large calorie deficit with intense training. Those on a high-protein diet gained lean mass and lost more fat than those on a lower-protein version.
Farhan does not need that level of training. Two sessions a week at the apartment gym, with squats, push-ups, rows and planks, plus his Saturday badminton, is enough of a signal. Many sports dietitians aim for between 1.2 and 1.6 grams of protein per kilo of body weight. For Farhan that is between 110 and 140 grams a day. Most of that can come from eggs, chicken, dal, curd and paneer. A whey shake is optional, not essential.
Sources: [5]
When is counting calories not enough?
When the numbers say you should be losing and the scale disagrees for months. Picture Farhan in January. He has held his 1,900 calories through Diwali and two weddings, logged every meal, and his waist has barely moved. He is also wearing a sweater in the office when nobody else is, and sleeping ten hours on Sundays. A thyroid running slow can lower his burn and leave him tired, and insulin resistance can make him hungrier. His app has no way of seeing either.
We should say where we stand, since you are reading this on our site. Metaboliq is a doctor-led weight programme, and the aim we set with members is "Lose up to 20% of your body weight — and keep your muscle". Results vary; your doctor decides what is right for you. It starts with a home blood test that a doctor reads. For Farhan, a thyroid and insulin result would show whether his deficit is the whole story, or whether something else needs treating first.
Sources: [7]