How many days do you start to lose fat from dieting and weight loss

Dieting for weight loss usually begins to deplete fat reserves 3-5 days later, depending on factors such as basal metabolic rate, exercise intensity, and dietary structure. Fat breakdown mainly occurs after the depletion of glycogen reserves, and common influencing factors include initial body weight, daily calorie deficit, and physical adaptability.

1. Glycogen depletion stage:

The human body first consumes glycogen from the liver and muscles for energy supply, and complete depletion takes about 48-72 hours. At this stage, weight loss mainly comes from water loss, and when the daily calorie deficit reaches 500 calories, it enters the fat supply stage around the third day. Monitoring urine ketone test strips can assist in determining the status of fat metabolism.

2. Metabolic mode transition:

When blood glucose levels remain below 3.9 mmol/L, glucagon activates lipase to break down triglycerides. There are individual differences in this physiological transition process, with individuals with a BMI ≥ 28 possibly initiating it 12 hours earlier, while those with high muscle mass may delay it until the 4th day.

3. Hormonal regulatory effects:

Changes in leptin and ghrelin levels directly affect fat mobilization efficiency. After 5 days of continuous dieting, a 40% decrease in leptin levels may trigger metabolic compensation, and it is recommended to use intermittent fasting to maintain hormone sensitivity. A week before a woman's menstrual period, an increase in progesterone can delay fat breakdown.

4. Exercise synergy effect:

Fasting aerobic exercise can trigger fat supply 12-24 hours in advance. Exercising for 30 minutes every day with a heart rate maintained at 60% -70% of maximum heart rate can increase fat oxidation efficiency by 19%. But it is necessary to avoid excessive exercise that can cause muscle breakdown.

5. Nutritional structure optimization:

Maintaining a protein intake of 1.6-2.2g/kg body weight can reduce muscle loss. Medium chain fatty acids such as coconut oil can directly enter mitochondria for oxidation, advancing the ketogenic process by 6-8 hours. Drinking more than 2000ml of water daily helps with the transport of fatty acids. Adopting a tiered calorie restriction is more beneficial for sustained weight loss than sudden fasting. It is recommended to reduce 300 calories per day in the first week and increase to 500 calories in the second week. Combining fasting and brisk walking for 20 minutes in the morning with protein supplementation such as whey protein before bedtime can maintain basal metabolic rate. Measuring waist circumference changes on a weekly basis is more accurate in reflecting weight loss progress than weighing. When a plateau occurs, the carbon water cycle method can be tried. Pay attention to supplementing with multivitamins and omega-3 fatty acids to prevent skin sagging and hair loss caused by dieting.