Intermittent Fasting Calculator

During fasting periods, you can consume water, black coffee, and plain tea without additives. Some fasting protocols allow small amounts of cream in coffee or bone broth, but these may technically break your fast. Avoid anything with calories, artificial sweeteners, or anything that might trigger an insulin response.

When done properly, intermittent fasting shouldn't cause significant muscle loss. The body tends to preserve muscle during short-term fasting by increasing growth hormone levels. However, ensuring adequate protein intake during eating windows and maintaining resistance training is important for muscle preservation. For more details, see our Weight Loss Guide.

Yes, many people successfully exercise while fasting. Low to moderate intensity workouts are generally well-tolerated. Some people prefer fasted cardio in the morning. For high-intensity or long-duration workouts, you might perform better if you schedule them near the end of your fasting period or after breaking your fast.

Most people notice initial changes (like reduced bloating and improved energy levels) within the first week. Visible fat loss typically becomes noticeable after 2-4 weeks of consistent practice. Metabolic improvements (like better blood sugar control) may take several weeks to months. Results vary based on your starting point, fasting protocol, diet quality, and other factors.

Intermittent fasting can be safe for many women, but some may need to modify the approach. Women's hormones can be more sensitive to calorie restriction, especially during reproductive years. Many women do well with shorter fasting windows (14-16 hours) or cycling fasting days. Women who are pregnant, breastfeeding, or have a history of eating disorders should avoid fasting.

The 16:8 method is generally the most beginner-friendly approach. It allows for an overnight fast plus skipping breakfast (or eating an early dinner). Our Beginner's Guide to Fasting provides a step-by-step approach to getting started. Some people find starting with 12:12 (12 hours fasting) and gradually increasing the fasting window works well.

You should continue taking prescribed medications as directed by your doctor. Some medications need to be taken with food - consult your healthcare provider about timing if you're fasting. Never stop or change medication without medical advice. Those on diabetes medications, blood pressure medications, or other drugs that might be affected by dietary changes should consult their doctor before starting IF.