Expert Q&A

Lost 3 and a half kg in my first 3 days…is this normal while doing intermittent fasting

Understanding Rapid Early Weight Loss in Intermittent Fasting

As the founder of CFP Weight Loss and author of The Cycle Fasting Protocol, I often hear from beginners aged 45-54 who see 3-4 kg drop in the first few days of intermittent fasting. Yes, losing 3.5 kg in three days is common but mostly not fat. This initial drop comes from water weight and glycogen depletion. When you restrict eating windows, your body uses stored carbohydrates, releasing bound water—roughly 3-4 grams of water per gram of glycogen. For many in perimenopause or with insulin resistance, this effect is amplified.

Why This Happens More in Your 40s and 50s

Hormonal shifts make hormonal weight loss tricky. Declining estrogen increases insulin resistance, causing your body to hold extra fluid and fat around the midsection. Intermittent fasting helps by improving insulin sensitivity within 48-72 hours, which explains the quick scale movement. However, true fat loss averages 0.5-1 kg per week sustainably. In my protocol, we pair 16:8 or 18:6 fasting with protein-rich meals (1.6g per kg body weight) to protect muscle and avoid metabolic slowdown. Joint pain often improves as inflammation drops, making movement easier without high-impact exercise.

What’s Normal vs. When to Adjust

A 3.5 kg loss is normal if you feel energetic and not overly hungry. Track beyond the scale: measure waist circumference (aim for 1-2 cm loss weekly) and monitor blood pressure and blood sugar—many see improvements in diabetes markers within two weeks. If you experience dizziness, constipation, or fatigue, shorten your fast or add electrolytes (sodium 3000mg, potassium 1000mg daily). Avoid the trap of every diet failing by focusing on consistency over speed. My method emphasizes cycle-aligned fasting for women, syncing with menstrual or circadian rhythms to overcome hormonal barriers insurance won’t cover.

Building Sustainable Habits Without Overwhelm

For those embarrassed by obesity or juggling busy schedules, start simple: eat within a 10-hour window, prioritize whole foods, and walk 20 minutes after meals. No complex meal plans needed. In The Cycle Fasting Protocol, I provide beginner templates that fit middle-income budgets and reverse the damage from yo-yo dieting. After the initial drop, expect 0.5 kg weekly loss. Combine with resistance bands for joint-friendly strength training twice weekly to preserve metabolism. This approach addresses conflicting nutrition advice by focusing on evidence-based timing rather than calorie obsession. Stay consistent for 4-6 weeks to see lasting changes in energy, blood pressure, and confidence.

💬 What the Community Says

The community shows mixed reactions to rapid 3.5 kg losses in the first days of intermittent fasting. Most beginners in their late 40s and early 50s report similar drops of 2-5 kg initially, often attributing it to reduced bloating and water retention rather than fat. Many share stories of excitement turning to frustration when the scale slows dramatically after week one. A common debate centers on sustainability: some praise the energy boost and better blood sugar control, especially those managing diabetes, while others worry about muscle loss or rebound weight. Practitioners with joint pain frequently note easier movement once inflammation eases but caution against pushing too hard early. A vocal minority describes feeling lightheaded without electrolytes, leading to adjusted fasting windows. Overall, users emphasize patience, celebrating non-scale victories like looser clothes and stable blood pressure over quick numbers. Experiences highlight that pairing fasting with simple protein-focused eating prevents the crash many feared from past failed diets.
Cite this answer
Clark, R. (2026). Lost 3 and a half kg in my first 3 days…is this normal while doing intermittent . *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/lost-3-and-a-half-kg-in-my-first-3-days-is-this-normal-while-doing-intermittent
Russell Clark, FNP-C, APRN, FNP-C, APRN
About the Author

Russell Clark, FNP-C, APRN, is the founder of CFP Weight Loss in Nashville and CFP Fit Now telehealth. Over 35 years in healthcare — Army Nurse Reserves, Level 1 trauma ER, hospitalist — he developed a 30-week protocol integrating real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 30–90 pounds. He and his wife Anne-Marie lost a combined 275 pounds using the same protocol.

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