The keto diet: macros, facts and low-carb recipes

• Carbs: 20-50 g a day, about 5-10% of calories. That is roughly the carbs in one to three slices of bread.
• Fat and protein: about 70-75% of calories from fat, about 20% from protein.
• For fat loss: not better than other diets when calories and protein are matched. What decides it is which one you can stick to.
• Not for everyone: not without medical advice if you are pregnant, under 18, have an eating disorder history or take diabetes medication.

What is the keto diet?

The ketogenic diet cuts carbs so low that the body starts using ketones made from fat for energy instead of glucose. This is called ketosis, and it usually sets in at 20-50 g of carbs a day, after a few days. The ketogenic diet has long been used under medical supervision in epilepsy; weight control is the other area with the most research.

Keto diet macros and the low-carb diet

“Low carb” and “keto” are not the same. A low-carb diet usually means 50-130 g of carbs a day; keto is stricter still. The table shows the grams for a 2,000 kcal day:

The limits vary a little between sources; these are the most common definitions. On keto you should not overdo protein, because part of it can turn into glucose; the usual plan takes about 20% of calories from protein.

What to eat and how many carbs are in it

On keto it is usual to count net carbs: carbs minus fibre. The table shows some common foods per 100 g:

Oil, meat and fish are practically carb-free, and eggs have only 0.7 g per 100 g. Avocado is popular for its few net carbs, and leafy greens and broccoli fit easily. Oats, rice and bread can push you past 50 g in a single serving, and among fruit the berries are the friendliest.

The first weeks: adaptation and the “keto flu”

After the switch many people feel tired, headachy and irritable for a few days, known as the “keto flu”. Part of it is water loss and lower electrolytes (sodium, potassium, magnesium). Once past it, most people adapt within a few weeks. The scale moves fast at first, but much of that is water and glycogen, not fat. Less fibre can cause constipation, so keep vegetables on the plate. If you feel unwell for long, stop and see a doctor.

What the research shows: is keto better for fat loss?

The short answer: no, when calories and protein are matched. Hall and colleagues (2016) studied in a hospital ward, on a controlled diet, what happens when carbs drop to keto levels at the same calories: fat loss did not speed up. Hall and Guo’s 2017 pooled analysis of controlled feeding studies is similar: on lower-carb diets energy expenditure rose by at most a small amount, but fat loss was not greater, and if anything tipped slightly toward the lower-fat diets.

The early results are big because glycogen binds water, and that water goes too. Over the long run what decides is whether you can stick to it. Some people are helped by keto’s appetite-reducing effect, others find the strict carb limit hard to keep. In some people LDL cholesterol rises, which is why it is worth keeping under medical supervision.

Low-carb recipes from us

20 of our recipes are low-carb: at most 20 g of carbs a serving, 6 of them at most 10 g. All are high in protein, so this is “high-protein low carb” rather than classic keto: fat gives 25-50% of calories, not 70%. For the classic keto ratio, add oil, avocado and nuts.

Dinner · 25 minParmesan Chicken & Asparagus341 kcal47 g proteinDinner · 20 minCreamy Spinach Chicken401 kcal52 g proteinLunch · 15 minChicken Avocado Salad336 kcal33 g protein

A sample day from our low-carb recipes

The day below has 39 g of carbs, so it sits within the keto range; 139 g of protein and 1,315 kcal. Fat gives 47% of calories. To push the fat share up, two tablespoons of olive oil and half an avocado take you further: about 1,723 kcal, fat at 58% of calories, but protein is still high, so it will not be classic keto.

Who should not do the keto diet?

If you take medication, especially for blood pressure or diabetes, cutting carbs suddenly can mean the dose has to change, and that is a doctor’s decision. A less strict, lower-carb diet is a safe starting point for most healthy adults, but there too calories and protein decide. Our weight loss guide covers the general steps.