Diet 50: 50 – principles and effects of the "alternate-day" diet
Oliwia Kaczmarek
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Diets Premium Expert • 24.09.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| Diets Premium Expert Oliwia Kaczmarek | min read 3 min | Scientifically reviewed by a clinical dietitian 24.09.2026 |
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Key Takeaways
It is established that conventional low-calorie diets seldom yield sustainable outcomes. Their lack of efficacy stems from the challenges individuals face in maintaining a restricted caloric intake over the long term without exceptions. Emerging frustration frequently results in breaking the rules and reverting to unhealthy habits, thereby nullifying prior efforts. The uniqueness of the 50:50 diet lies in alleviating this pressure by enabling meal consumption without calorie tracking, and even nearly every day.
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The 50:50 Diet – Dr. Krista Varady's Research
In 2009, the results of a study by Dr. Kristy Vardy and colleagues were published showing the efficacy of a 50:50 diet. This study looked at the effects of diet on body weight and cholesterol levels in obese people who used the diet every other day. The results were promising. They saw an average weight loss of about 6% of baseline weight over 8 weeks, and heart disease risk indicators, such as triglyceride levels, also improved.
The Alternate-Day Fasting Concept
This diet involves consuming 25% of the recommended daily energy intake every other day. On the other days, you can eat whatever you want to eat. You should only limit your fat intake to 30% of your daily calorie intake, which is unambiguous to consuming only low-fat meat and semi-fat dairy products.
The 50:50 Diet – Food Selection and Meal Quality
As with any diet, it is best to consume only foods high in nutrition, full of valuable vitamins and minerals. According to the ICE's recommendations, to ensure adequate fiber intake, we should choose on a reduction diet or not full-grain baked goods, whole processed flour, fresh vegetables and fruits. We should avoid sugar and animal fats.
The 50:50 Diet – Metabolic Effects and Results
As Dr. Vardy's research has shown, the effects of diet are satisfactory. First of all, it's because of the general simplicity of the recommendations. It's easier to deny ourselves what we like when we have the prospect of being able to eat well. The weight loss effect is not achieved if the energy balance in the weekly sense is positive. However, balancing the restrictions from these few days of hunger is not so easy if we eat only the most valuable products and avoid those high-energy foods that lack any valuable ingredients. So the condition for achieving the effects is not to maintain a calorie regime for a few weeks, but to eat everything when we can allow this food to stay healthy.
Oliwia Kaczmarek
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