Intermittent Fasting
OMAD Diet (One Meal a Day)
One meal per day, consumed in a 1-hour window. The remaining 23 hours: only water, tea or coffee without calories. Extreme form of 23:1 intermittent fasting.
OMAD (One Meal A Day) is the most extreme form of intermittent fasting: all daily calories are consumed in a single meal within a 1-hour eating window, with the remaining 23 hours in a complete fast (water, tea or coffee without calories only).
The claimed appeal: extreme simplicity (only one meal to plan), strong metabolic effects of the prolonged fast, and significant weight loss. The real risks: it is very difficult to provide all necessary nutrients in a single meal, which creates a long-term deficiency risk; the prolonged fast can trigger binge-eating episodes in susceptible individuals; and performance and daily functioning can be significantly affected.
OMAD is not recommended as a long-term lifestyle by major nutritional organisations and has very limited rigorous clinical data compared to less extreme IF protocols (16:8 or 5:2).
History and origin
OMAD does not have a specific founding author but emerged organically from the intermittent fasting community in the 2010s, particularly through online forums and later YouTube channels. As the 16:8 IF protocol gained popularity, a subset of practitioners began experimenting with progressively longer fasting windows — 18:6, 20:4, 23:1 — reporting increasingly dramatic results.
The OMAD term was popularised especially through Reddit (the r/OMAD community formed around 2016 and grew rapidly) and YouTube channels documenting personal transformations. The community developed its own vocabulary, protocols and culture — including debates about what can be included in the 1-hour window, whether coffee breaks the fast, and whether OMAD is compatible with strength training.
There is no single “founding” text for OMAD — its origin is collective and internet-driven, which differentiates it from commercial diets with authors and books. This also means there is less structure and accountability: results reported by community members are anecdotal, and it is left to the individual to navigate the risks. The few academic studies that have examined very-short-eating-window protocols (22:2 or 23:1) have found short-term metabolic benefits comparable to standard IF protocols, but raise concerns about the adequacy of nutritional intake and long-term sustainability.
+ What you eat and what you avoid
✓ What you eat
- All food is allowed — but only in a 1-hour window
- The meal should be nutritionally complete and rich in protein, healthy fats and fibre
- Water, tea and coffee (without sugar or milk) throughout the day
✕ What you avoid
- Any food outside the 1-hour eating window
- Caloric beverages during the fasting period
+ Sample one-day menu
+ Pros and cons
Pros
- Extreme simplicity — no planning for most of the day
- Strong metabolic effects from the prolonged fast
- Reduced food expenses
Cons
- Very difficult to consume all necessary nutrients and calories in a single meal
- High risk of nutritional deficiency long-term
- Can trigger or worsen binge eating
- Difficult to follow socially
- Not suitable for people on medication requiring food
- Very limited long-term clinical studies
+ ⚠️ Who should avoid this diet
- People with diabetes or hypoglycaemia
- Pregnant or breastfeeding women
- People with eating disorders (anorexia, bulimia, binge eating)
- People on medication requiring regular meals
- Children and adolescents
- Not recommended without medical supervision for people with chronic diseases
Indicative list. Before starting any diet, especially if you have a medical condition, consult a doctor or nutritionist.
Întrebări frecvente
Is OMAD safe?
For healthy adults without chronic disease or eating disorders, short-term OMAD seems to be tolerated by some people. Long-term, the risk of nutritional deficiency is significant because it is very difficult to cover all micronutrient needs in a single meal. It is not recommended as a long-term lifestyle without medical monitoring.
Can I follow OMAD and exercise?
Intense physical training on OMAD is problematic: without pre- and post-workout nutrition, recovery and performance are affected. Many OMAD practitioners time their meal around training. For high-performance athletes, OMAD is generally not compatible with performance goals.
Is OMAD just a form of intermittent fasting?
Yes — OMAD is the most extreme variant of intermittent fasting: the ratio is 23:1 (23 hours fasting, 1 hour eating). Common IF protocols (16:8, 18:6) are much less restrictive. OMAD is generally considered beyond standard IF recommendations.