16:8 is the most popular way to fast for a simple reason: it fits real life. Sixteen hours off, eight hours on. Here's how to actually make it stick.
How 16:8 works
The classic setup is eating from noon to 8 p.m. and fasting from 8 p.m. to noon the next day. Most of those sixteen hours happen while you're asleep, which is why it's the easiest fast to live with.
The window doesn't have to be noon to 8. If you train at 6 a.m., or your family eats dinner early, slide it. Consistency matters more than the exact hours. And if sixteen feels brutal right away, start at 12 or 14 and work up. That gradual approach is what de Cabo and Mattson suggest in their 2019 review of intermittent fasting in the New England Journal of Medicine.
What the first month usually feels like
We're not going to give you a week-by-week script. Nobody's body reads the script.
What's fair to say: early on, a lot of people feel hungry around their old breakfast time, and some feel irritable or foggy. According to de Cabo and Mattson, those early side effects usually fade within about a month. After that, for many people, the fast just becomes part of the day. Some adapt faster, some slower. If you're still miserable after several weeks, a shorter fast might simply suit you better, and that's fine.
Three rules that make or break 16:8
Rule 1: Open with protein. Make your first meal a real one, built around protein. For people who train, the International Society of Sports Nutrition suggests about 20 to 40 g per meal. With only an eight-hour window, you've got fewer meals to hit your daily total, so the first one counts.
Rule 2: Don't neglect sodium and fluids. Insulin helps your kidneys hold on to sodium. With insulin lower for longer stretches, you can lose more sodium and water than you're used to. For some people that shows up as headaches, lightheadedness or low energy. Drink water through the fast and salt your food. We cover it in more depth in our electrolyte article.
Rule 3: Keep training. A shorter eating window doesn't have to cost you muscle if you keep lifting and eat enough protein. In an eight-week study of resistance-trained men on a 16:8 schedule, fat mass dropped while fat-free mass and strength held up (Moro et al.). Creatine monohydrate, typically 3 to 5 g a day, is one of the best-studied supplements for strength and lean mass alongside training, according to the ISSN's position stand. More on creatine and fasting here.
What to drink during your fast
- Water, as much as you want
- Black coffee
- Plain tea, no sugar, no milk
- Sparkling water, unsweetened
Anything with sugar, milk or real calories puts food back into the picture. Where exactly the line sits for things like a splash of cream depends on what you're fasting for, so be honest with yourself.
Keep your expectations honest
- Eating too little in the window. You'll burn out and your training will suffer.
- Eating junk in the window. The clock doesn't cancel bad food.
- Expecting the schedule to do all the work. In the TREAT trial, adults eating on a noon-to-8 p.m. schedule for 12 weeks didn't lose significantly more weight than people eating normally. 16:8 is a tool that makes eating well easier for a lot of people. It isn't a shortcut.
If you're pregnant or breastfeeding, take medication for diabetes or blood pressure, or have a history of disordered eating, check with your doctor before starting.
We're working on Lyte & Loaded, electrolytes plus creatine with zero sugar and zero calories, built for people who fast and train. It's not available yet, but you can join the waitlist if you want to know when it drops.
Pick your window, protect your protein, keep lifting. Feed the mission. Not the hunger.
This article is for information only and isn't a substitute for advice from a health professional.
Sources: de Cabo R, Mattson MP, "Effects of Intermittent Fasting on Health, Aging, and Disease," New England Journal of Medicine, 2019; Lowe DA 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 Internal Medicine, 2020; Moro T et al., "Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males," Journal of Translational Medicine, 2016; DeFronzo RA, "The effect of insulin on renal sodium metabolism," Diabetologia, 1981; Jäger R et al., "International Society of Sports Nutrition Position Stand: protein and exercise," Journal of the International Society of Sports Nutrition, 2017; Kreider RB et al., "International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine," Journal of the International Society of Sports Nutrition, 2017.