However, it's important to note that extreme diets like the one you've described may not be healthy or sustainable in the long run and could have negative effects on your health.
Eating 500-800 calories a day is considered an extremely low-calorie intake and may not provide your body with the necessary nutrients it needs to function properly. Such restrictive diets can lead to nutrient deficiencies, muscle loss, a slowdown in metabolism, and other health issues.
Additionally, consuming 3000-4000 calories in one day, especially after being in a severe calorie deficit throughout the week, can be a shock to your system. Your body may store these excess calories as fat, negating any progress you may have made during the week.
If your goal is to lose weight, it's generally recommended to adopt a balanced and sustainable approach to eating. A safe and effective weight loss plan usually involves creating a moderate calorie deficit (typically 500-1000 calories below your maintenance level) by reducing calorie intake and increasing physical activity. This approach allows you to lose weight at a steady and healthy pace.
Consulting a registered dietitian or healthcare professional can help you create a personalized plan that aligns with your specific health needs, weight loss goals, and lifestyle. They can guide you on making healthier food choices, portion control, and establishing a consistent exercise routine.
Remember, the key to successful weight management is to adopt sustainable habits that you can maintain over time rather than resorting to extreme and potentially harmful practices.