16/8 vs 18/6 vs OMAD: Which Fasting Schedule Fits You?

_By the PingDiet Editorial Team · Last updated October 12, 2026_

Short answer: In head-to-head research, longer daily fasts don't reliably beat shorter ones once total calories are similar. 16/8 (an 8-hour eating window) is the easiest to sustain and the most studied. 18/6 tends to cut a little more food but is harder to stick with. OMAD (one meal a day) makes it difficult to get enough protein and nutrients and, in one controlled trial, raised hunger and blood pressure [1]. For most people, the best schedule is the one they can keep for months.

The three schedules at a glance

What studies show about 16/8

The best-known trials are reassuring but modest. In the year-long trial by Liu and colleagues, adding an 8-hour eating window to calorie restriction didn't produce more weight loss than calorie restriction alone [2]. In the TREAT trial, a 16:8 schedule without calorie guidance led to about 1 kg of weight loss, not significantly different from the control group [3]. Takeaway: 16/8 is a helpful way to structure eating, not a metabolic shortcut.

Does 18/6 work better?

Cienfuegos and colleagues compared 4-hour and 6-hour windows over 8 weeks. Both groups ate about 550 fewer calories a day and lost about 3% of body weight, with no significant difference between the two windows [4]. A shorter window may simply make it easier to eat less. If 16/8 isn't moving the scale, adjusting what you eat in the window is usually more effective than shrinking it.

The trouble with OMAD

In a controlled crossover study, healthy adults ate the same calories either as one evening meal or as three meals. On one meal a day, they reported more hunger and had higher blood pressure and total cholesterol, alongside a small fat loss [1]. Eating all your protein, fiber and micronutrients in one sitting is hard, and large late meals can disrupt sleep. OMAD isn't appropriate for people with diabetes on glucose-lowering medication, anyone with a history of disordered eating, or older adults trying to preserve muscle.

How to choose

• New to fasting: Start at 12–14 hours, then move to 16/8.
• Comfortable on 16/8 and want a change: Try 18/6 on weekdays and 16/8 on weekends.
• Considering OMAD: Try two meals in a 6-hour window first; it gets most of the convenience with fewer downsides.
• In any case: Count your Pings, not your hours. Fewer eating events with real protein at each one matters more than the exact clock.

Sources

1. Stote KS, et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am J Clin Nutr. 2007;85(4):981-988.
2. Liu D, et al. Calorie restriction with or without time-restricted eating in weight loss. N Engl J Med. 2022;386(16):1495-1504.
3. Lowe DA, et al. Effects of time-restricted eating on weight loss and other metabolic parameters. JAMA Intern Med. 2020;180(11):1491-1499.
4. Cienfuegos S, et al. Effects of 4- and 6-h time-restricted feeding on weight and cardiometabolic health. Cell Metab. 2020;32(3):366-378.