Why the Weight Stops Coming Off, Even When You Keep Trying

Week one: three kilos gone. You have never felt more capable. Almost none of it was fat.

Your body stores carbohydrate as glycogen, and each gram holds about three grams of water. Eat less, burn the store, and the water leaves with it. That is why every diet works brilliantly for a week, and why the second week feels as if the diet broke.

The number on the scales

Your weight swings by a kilo or two within a single day. Almost all of that is water, salt, carbohydrate and hormones.

Comparing one day with the next is mostly noise. Comparing one week with the next is mostly signal. People give up on a Tuesday because of a number that was never about fat.

Your body defends a range

Your body does not have a target weight. It has a defended range.

Fat is an organ, and it talks. It releases a hormone that tells the brain how much fuel is in reserve. When the reserve falls, the brain reads it as a shortage, not a diet. What follows is a system trying to save your life.

Lever one: hunger

The hormone that says "enough" is released in smaller amounts. The one that says "eat" is released in larger amounts. This persists for a year or more.

People think hunger is a phase they failed to push through. It is a setting that was changed.

Lever two: energy

A smaller body burns less. But it also burns less than its new size predicts. You move less without deciding to: smaller gestures, less fidgeting, fewer stairs.

Put the two together and the weight stops moving, although your effort has not changed. This is the point where people decide they have no willpower. They have a thermostat, and it is winning.

Why not just move more?

Exercise is one of the best things you can do for almost every organ. On its own, it is one of the weakest tools for losing weight.

When you add exercise, the body quietly subtracts activity elsewhere, and appetite rises a little. Exercise protects your muscle, your heart and your mind. It is a poor lever on the scales.

Two free dials

• Sleep. Short sleep raises the hunger hormone and lowers the fullness hormone.
• Stress. The stress hormone stays high, and appetite follows.

If sleep is broken, the diet is being fought on two fronts.

What the food is

In a careful experiment, two groups were offered meals matched for calories, protein, fat and sugar. One group's food was heavily processed. That group ate about 500 calories a day more, without noticing.

Processing does not add calories. It removes the friction that tells you to stop.

After the diet

The hunger is still turned up and the furnace is still turned down. So the weight returns, often faster than it left. That is not the person failing. The system was built for a world where a shortage could kill you.

People also lose fat and some muscle, and then regain mostly fat. That is a reason to go slower once, not a reason for despair.

What helps

• Go slower. A smaller deficit produces a smaller defence.
• Eat enough protein and do resistance training. They do not speed things up. They protect muscle.
• Plan for maintenance. It is the hardest part, and it lasts.

People who keep weight off have been followed for years. They weigh themselves regularly to catch a small drift. They eat consistently, including at weekends. They move a lot on most days. They treat a bad week as a week.

Surgery and injections

Weight-loss surgery does not mainly work by making the stomach smaller. Rerouting the gut changes the hormones it sends to the brain. It is a major operation with real risks.

The newer weight-loss injections are not fat burners. They copy a gut hormone that slows the stomach and tells the brain the shortage is over. That is also why weight tends to return when people stop taking them.

Whether either is right for you is a decision to make with a doctor.

When it may be something else

• An underactive thyroid slows the whole system. It is common and easily tested.
• Polycystic ovary syndrome changes how the body handles insulin.
• Some medicines cause weight gain, including some antidepressants, antipsychotics and steroids.

Do not stop a prescribed medicine on your own. Say "I am doing everything right and nothing is moving" to a doctor.

The short answer

Losing weight is not hard because you are weak. It is hard because it is defended. If you have fought this for years and assumed it was a character problem, it was never that.