Food facts

Food Facts: What Really Belongs in a Slimming Diet

No single food makes you gain or lose weight — total energy over time does. But some foods make a calorie deficit far easier to stick to. Fill half your plate with vegetables, a quarter with lean protein and a quarter with wholegrain or starchy carbohydrates, and use fats sparingly.

Last reviewed: 22 October 2026

Bowls of oats, kidney beans, red lentils, berries and wholemeal bread

The macronutrients at a glance

Every food is made up of some mix of protein, carbohydrate and fat (plus alcohol, if you drink). They differ in energy per gram:

Approximate energy per gram (UK food labelling values)
Nutrient	kcal per gram	Slimming role
Protein	4	Most filling; helps preserve muscle
Carbohydrate	4	Main energy source; choose high-fibre types
Fibre	2	Adds bulk, slows digestion, supports gut health
Alcohol	7	Provides energy but no nutrients; lowers resolve
Fat	9	Essential in small amounts; very energy-dense

Fats: smaller portions, better types

Fat isn't the enemy, but at 9kcal per gram a heavy pour of oil can add 100–200kcal to a meal without you noticing. Measure oil with a spoon or use a spray, and favour unsaturated fats such as olive and rapeseed oil, nuts and oily fish.

The NHS advises keeping saturated fat (butter, fatty meat, pastry, cream) to no more than 30g a day for men and 20g for women.

Carbohydrates are not the problem

Bread, rice, pasta and potatoes have been unfairly blamed for weight gain. It is usually what we add to them — butter, cheese sauce, frying — that piles on the calories. Wholegrain versions provide more fibre and keep you full for longer.

Protein for fullness

Including a source of protein at every meal — eggs, Greek yoghurt, chicken, fish, tofu, beans or lentils — is one of the simplest ways to feel satisfied on fewer calories.

Vegetables, fruit, beans and pulses

These are the backbone of any slimming diet: high in water and fibre, low in energy density. Frozen and tinned (in water or juice) count just as much as fresh. Aim for at least five portions of fruit and vegetables a day; beans and pulses count as one portion however much you eat.

Find out why fibre matters in our facts about fibre guide.

Common myths, quickly busted

'Eating after 8pm makes you fat.' Total intake matters more than the clock, though late snacking is often where extra calories creep in.
'Detox teas burn fat.' Your liver and kidneys handle detoxing. Most 'detox' products are laxatives or diuretics.
'Low-fat always means low-calorie.' Some low-fat products replace fat with sugar. Check the kcal per portion on the label.
'You must cut out sugar entirely.' Reducing free sugars helps, but an occasional treat can fit — see our treats under 100 calories.

In this section

Facts about fibreWhy dietary fibre helps you slim, the best high-fibre UK cupboard staples and easy ways to reach the recommended 30g a day.Potatoes and carbohydratesWhy the humble British potato and wholegrain carbohydrates can be part of a slimming diet, with the best cooking methods and sensible portion sizes.Hydration and weight lossHow staying well hydrated supports weight loss, helps you tell thirst from hunger, and simple ways to drink more throughout the day.Treats under 100 caloriesTwenty sweet and savoury snacks under 100 calories that you can find in any UK supermarket — for curbing cravings without derailing your goals.

A new free meal plan every Monday

Balanced UK menus with a matching shopping list, published here on the site. Look back at previous weeks any time.

See this week's plan