ML Performance CoachingFree guide

Diets compared: what the research says

Keto, low-fat, fasting, Mediterranean, plant-based. Which one wins? Probably none of them.

At a glance

In well-run trials, no single diet beats the others for fat loss.
The best diet is the one you can follow for a year, not 3 weeks.
What works across all of them: protein, vegetables, fibre, portions and sleep.

What the best trials found

Low-fat vs low-carb. The DIETFITS trial followed 609 adults for 12 months. Both groups lost weight: about 5.3 kg on a healthy low-fat diet and 6.0 kg on a healthy low-carb diet. The difference was not statistically significant, and neither genes nor insulin response predicted who did better on which.

Fasting windows. In a 12-month trial of 139 adults with obesity, eating only between 8am and 4pm on top of calorie control gave no significant extra weight loss versus calorie control alone (8.0 kg vs 6.3 kg, difference not significant).

The main approaches side by side

Approach	What it is	Honest summary	Watch out for
Low-carb / keto	Fewer carbohydrates, more fat and protein	Comparable weight loss to low-fat in the DIETFITS trial. Some people find it filling and easy to follow.	Hard to sustain socially. Fibre and variety can drop. Can feel poor for high-intensity training.
Low-fat	Fewer fats, more carbohydrate	Same result as low-carb in DIETFITS when the diet is high quality.	Low-fat does not mean low quality. Biscuits are still biscuits.
Intermittent fasting / time-restricted eating	Eating within a window, or fasting some days	Works if it helps you eat less. No clear extra benefit over simple calorie control in the trial above.	Training late in a fast, low energy, overeating when you break it.
Mediterranean style	Vegetables, fruit, legumes, fish, olive oil, whole grains	Widely recommended for overall health. A pattern of eating, not a short diet.	Portions still matter if fat loss is the goal.
Plant-based	Mostly or entirely plants	Can meet your needs with planning. Pays off in fibre and variety.	Plan protein. Vegans need vitamin B12 (NHS advice).
High-protein	Protein at every meal	Helps fullness and keeping muscle while dieting. See our protein guide.	Check protein sources are not mostly processed.

Choose with these 4 questions

Can I eat this way at a birthday, a work lunch and on holiday?
Does it fit the foods I already enjoy?
Do I have the energy to train properly on it?
Could I still be doing this in 12 months?

Whatever you pick, the winning habits are the same: enough protein, plenty of vegetables and fibre, sensible portions, regular strength training, and 7 to 9 hours of sleep. If you have a medical condition, are pregnant, or have ever had a difficult relationship with food, speak to your doctor or a registered dietitian before changing how you eat.

Set calories and protein for your goalFree macro calculator on our website. ml77performance.co.uk#macros

Written by Maor Lilov, strength and conditioning coach working in men's professional football. BSc (Hons) Strength & Conditioning Science in progress. UKSCA member.

Not medical advice. This guide is general information for healthy adults. Speak to a doctor or registered healthcare professional before changing your exercise or diet, especially if you have a medical condition, an injury, are pregnant or breastfeeding. Sources: Gardner et al., DIETFITS randomized clinical trial, JAMA 2018 (healthy low-fat vs healthy low-carbohydrate, 12 months, n = 609). Liu et al., Calorie restriction with or without time-restricted eating in weight loss, New England Journal of Medicine 2022 (n = 139). NHS: vegetarian and vegan diets. © ML Performance Coaching.