What Alternate-Day Fasting Does To Your Body

Alternate-day fasting is a type of intermittent fasting that involves alternating between 24-hour periods of fasting and regular eating. The overall goal of this diet is to promote weight loss and improve heart health. On fasting days, you can either skip food for an entire day or reduce your caloric intake to 25% of your typical daily caloric needs (via Healthline). For people who usually follow a 2,000-calorie diet, this means only consuming 500 calories per day on fasting days.

This would be considered moderate alternate-day fasting and involves eating and drinking low-calorie foods and beverages that help keep you hydrated and feeling full. This means sticking to noncaloric drinks like water or coffee, and eating foods that are high in fiber and protein (via Greatist). Even if you're not taking the modified approach, you should still make sure you stay hydrated and drink plenty of water. On feasting days, however, you're free to eat and drink whatever you want!

The main objective of alternate-day fasting is to promote weight loss by significantly reducing your weekly caloric intake — but is this a safe and effective way to lose weight? Although alternate-day fasting is generally considered safe for most healthy adults, it's not for everyone and it is no more effective than other calorie-restrictive diets (via Healthline). While studies have shown that alternate-day fasting can certainly help you burn calories and lose weight, there is no scientific evidence to suggest that it can help you lose more weight than other low-calorie diets. 

There's also the possibility that not eating all day on fasting days can deprive your body of essential nutrients and potentially lead to dehydration. That's why it's important to be extra vigilant about what you're eating and how much water you're drinking on both fasting and feasting days. Regardless of the circumstances, however, there are certain people who should avoid following this type of diet (via Greatist). Alternate-day fasting is not recommended for children, people who are pregnant or breastfeeding, people diagnosed with an eating disorder, people who take certain medications or have ongoing health issues, and people who are clinically underweight.

If you are struggling with an eating disorder, or know someone who is, help is available. Visit the National Eating Disorders Association website or contact NEDA's Live Helpline at 1-800-931-2237. You can also receive 24/7 Crisis Support via text (send NEDA to 741-741).