How much weight can you lose by fasting?

Weight changes during fasting vary significantly by individual and depend on fasting duration, starting weight, diet quality, and activity level. Initial changes are often water and glycogen rather than fat ( 13 ). Individual results vary considerably, and long-term sustainable weight management typically requires a broader dietary approach.

How much water should I drink during intermittent fasting?

General adult hydration guidance (approximately 2–2.7 liters for women, 2.5–3.7 liters for men) applies during intermittent fasting ( 7 ). Thirst and urine color are the most practical guides. Some people find they need to drink more during the fasting window to manage hunger.

Can you drink coffee during a water fast?

Technically, plain black coffee breaks a strict water-only fast as it is not water. However, many people include plain black coffee in a modified water fast or IF approach, as it contains minimal calories and does not significantly affect the fasted metabolic state for most people. Whether to include it depends on your specific fasting protocol.

What are the benefits of a water fast?

Some research has explored associations between water fasting and various physiological processes including autophagy, metabolic markers, and blood glucose patterns ( 13 ). Much of this research is preliminary or based on animal studies, and individual responses vary.

How long is it safe to water fast?

Most guidance suggests that water fasts beyond 24–72 hours carry increasing risks and should only be undertaken with medical supervision. A 24-hour water fast is the most commonly explored duration in research ( 13 ). Extended fasts (72+ hours) are not recommended for most people without healthcare provider guidance to ensure the process is manageable.

What can I drink during intermittent fasting besides water?

Plain black coffee, unsweetened herbal and green tea, plain sparkling water, and plain electrolyte water (without sweeteners) are widely considered acceptable during most IF approaches. Bone broth contains some calories but is used in many modified fasting protocols. Avoid sweetened drinks, milk, cream, juice, and alcohol during the fasting window.

Does drinking water speed up weight loss during fasting?

Water does not directly cause weight loss. However, adequate hydration during fasting may help manage hunger, support energy levels, and maintain normal bodily function. Some research suggests that drinking water before eating may reduce meal size for some people, but direct causal weight loss from water alone is not supported ( 21 ).