What to eat during intermittent fasting

Why food still matters

A fasting window helps mainly by making it easier to eat less without counting ³. It doesn't make what you eat irrelevant. When people simply ate between noon and 8 p.m. with no other advice, they lost no more weight than people eating three meals a day, and they lost a little more lean mass ⁴. Fewer meals means each one has more work to do: it has to keep you full until your next window and give your body enough protein.

Build your plate

Part of the plate	Good choices	Why
Protein, about a quarter	Eggs, fish, chicken, tofu, tempeh, Greek yoghurt, cottage cheese, lentils, beans	Keeps muscle while you lose fat and helps you feel full 5,1
Vegetables, about half	Salad, greens, broccoli, peppers, carrots, tomatoes, frozen mixed vegetables	Fibre and volume for few calories, and potassium and magnesium
Fibre-rich carbs, about a quarter	Wholegrain bread, oats, brown rice, potatoes, beans, whole fruit	Fibre feeds your gut bacteria 6
A little fat	Olive oil, nuts, seeds, avocado	Flavour, and it helps you absorb some vitamins

You don't need to weigh anything. Think of it as a shape: protein in every meal, vegetables taking up the most room, and starch as the side rather than the main event.

Your first meal: what to eat first

After a fast you don't need a juice, a ritual or a supplement. A normal, balanced meal is perfect. But the order you eat it in matters more than most people think.

The same held in people with prediabetes: putting protein and vegetables first cut the blood sugar response by about 39% and kept glucose much steadier ⁷. So eat the salad or vegetables and the protein first, and leave bread, rice, pasta, fruit and anything sweet for the end. Good first meals: an omelette with vegetables and toast, Greek yoghurt with nuts and berries, or a salad with chicken or chickpeas and some bread. See how to break a fast for more.

Your last meal: carry yourself through the fast

• Make it a real meal, with protein and fibre, rather than a snack. It's what carries you through the evening.
• If you can, make dinner earlier and lighter than lunch. Your body handles glucose best in the morning and around midday ⁸.
• There's no need to load up. In trials, people with a short window usually ate less overall, not more ⁹.
• Finish with water rather than a sweet drink, and start your timer when you're done.

How much protein?

If you're losing weight and active, 1.2 to 1.6 g of protein per kilo of body weight a day is a good range, and gains from strength training level off at about 1.6 g ¹⁰: about 110 g for someone who weighs 70 kg. Your body can use a large serving well, so two generous meals work ¹¹. The protein calculator works out your own number.

Fibre and your gut

Aim for at least 25 g of fibre a day from vegetables, fruit, legumes, whole grains, nuts and seeds. People who ate 25 to 29 g a day or more had the lowest rates of heart disease, type 2 diabetes and bowel cancer ⁶. Fermented foods such as plain yoghurt, kefir or kimchi made gut bacteria more diverse in a small Stanford trial ¹². Fewer meals can mean less fibre, so if you get constipated while fasting, add fibre slowly and drink more water.

MYTH

You can eat anything you like in your window.

FACT

You can, but it changes the results. The window works mostly by helping you eat less ³, and what you eat still shapes your health: in one year-long trial, LDL cholesterol rose more in the fasting group ¹³. Protein, plants and fibre make the habit work.

Sources

1. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S-1329S. doi.org/10.3945/ajcn.114.084038
2. Shukla AP, Andono J, Touhamy SH, et al. Carbohydrate-last meal pattern lowers postprandial glucose and insulin excursions in type 2 diabetes. BMJ Open Diabetes Res Care. 2017;5(1):e000440. doi.org/10.1136/bmjdrc-2017-000440
3. Liu D, Huang Y, Huang C, et al. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. N Engl J Med. 2022;386(16):1495-1504. doi.org/10.1056/NEJMoa2114833
4. Lowe DA, Wu N, Rohdin-Bibby L, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med. 2020;180(11):1491-1499. doi.org/10.1001/jamainternmed.2020.4153
5. Wycherley TP, Moran LJ, Clifton PM, et al. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;96(6):1281-98. doi.org/10.3945/ajcn.112.044321
6. Reynolds A, Mann J, Cummings J, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434-445. doi.org/10.1016/S0140-6736(18)31809-9
7. Shukla AP, Dickison M, Coughlin N, et al. The impact of food order on postprandial glycaemic excursions in prediabetes. Diabetes Obes Metab. 2019;21(2):377-381. doi.org/10.1111/dom.13503
8. Poggiogalle E, Jamshed H, Peterson CM. Circadian regulation of glucose, lipid, and energy metabolism in humans. Metabolism. 2018;84:11-27. doi.org/10.1016/j.metabol.2017.11.017
9. Cienfuegos S, Gabel K, Kalam F, et al. Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metab. 2020;32(3):366-378.e3. doi.org/10.1016/j.cmet.2020.06.018
10. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. doi.org/10.1136/bjsports-2017-097608
11. Trommelen J, van Lieshout GAA, Nyakayiru J, et al. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell Rep Med. 2023;4(12):101324. doi.org/10.1016/j.xcrm.2023.101324
12. Wastyk HC, Fragiadakis GK, Perelman D, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137-4153.e14. doi.org/10.1016/j.cell.2021.06.019
13. Trepanowski JF, Kroeger CM, Barnosky A, et al. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Intern Med. 2017;177(7):930-938. doi.org/10.1001/jamainternmed.2017.0936
14. Grajower MM, Horne BD. Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients. 2019;11(4):873. doi.org/10.3390/nu11040873