Carbs at night, yes or no? When, how much and what kind.

Client dinner, the waiter hovering. Carbs at night, yes or no? You made your mind up a month ago. Steak and a side salad, no chips, no bread. It's the same at home, and the grapes sit in the fridge because they're full of sugar.

Then comes the next question. To lose weight fast, should I just eat protein? I hear it a lot from the people I work with. The answer is no.

How to spot a fear of carbs

• The scales agreed with you straight away. Your weight fell fast for a few days, then stopped.
• You're wired in the evening. Dinner is just meat or fish, and in bed your mind won't switch off.
• Even fruit worries you. Grapes, bananas, figs. You eye them like pudding.

Do carbs at night make you gain weight?

No more than at lunch. You gain weight when more comes in over the day than you burn, whatever the time. In one six-month comparison, two groups of men with a lot of weight to lose ate the same calories. Both lost weight, and those who ate nearly all their carbs at dinner lost more from their waist. That's a single comparison, so I don't make it a rule. It does show you can lose weight with carbs at dinner.

The first kilos are mostly water. Your body keeps a store of sugar in your muscles and liver, with plenty of water. Cut the carbs, the store empties, the water goes and the scales drop. Fat goes later, and it goes because without pasta, bread and puddings you eat less.

Over time your body adapts. After months on very few carbs, thyroid hormones can fall, so can the fullness hormone, and you risk losing muscle too. You also lose the knack of handling them. When they come back you may bloat and cope less well.

A protein-only dinner can leave you wired. Carbs help your brain make serotonin, which turns into melatonin at night. That's why carbs at night help some people sleep.

When, how much and what kind

What kind. The ones you have to chew. Potatoes, pulses, wholegrain rice or pasta, proper bread. They reach your blood more slowly than sweets and pastries, especially in a full meal.

How much. A normal portion, eaten last, after vegetables and protein. The fibre gets there first and slows the sugar. No bread alongside pasta or potatoes. Bigger if you trained that afternoon, because after exercise your muscles take up sugar more easily. Smaller if you've sat at a desk all day.

When. Dinner is fine, provided it stays light. A very large or fatty meal just before bed can disturb your sleep more than carbs do.

If you'd cut them out, come back gradually. A small portion for a few days, then a normal one. Within a couple of weeks your body usually handles them again and the bloating tends to settle.

Start with tonight's dinner, without weighing anything. Then watch your sleep, hunger and waist for a few weeks. Some people do better with more carbs at lunch and fewer in the evening. If that's you, move them.