Losing 5 pounds in a week is possible, mostly from water weight at the start of a diet. A sustainable pace is 1 to 2 pounds a week.
Is it normal
It’s possible, especially in the first week of a diet, because of water and glycogen loss.
Safe rate
The CDC recommends 1 to 2 pounds a week.
Fat
It takes a 3,500 calorie deficit to lose a pound of fat.
Risks of fast loss
Muscle loss, gallstones and nutrient gaps.
See a doctor
If you lose weight rapidly without trying.
Sustainable
Slow, steady changes work best.
What the numbers mean
Losing 5 pounds in a week is possible, especially in the first week of a diet, but much of it is water and glycogen. Fat loss requires a calorie deficit, and a pound of fat holds about 3,500 calories, so 5 pounds of fat in a week would need a daily deficit of about 2,500 calories, which is not safe for most.
- The CDC says losing 1 to 2 pounds per week is a safe, sustainable rate.
- Low carbohydrate diets cause quick early weight loss from water, since each gram of glycogen holds roughly 3 grams of water.
- Illness, dehydration, medications or conditions such as hyperthyroidism and cancer can cause unintentional weight loss.
Risks and when to check
Rapid weight loss raises risk of gallstones, muscle loss, nutrient deficiency and fatigue. Unintentional loss of more than 5 percent of body weight in 6 to 12 months should be evaluated by a doctor. Weight loss with night sweats, persistent fever, fatigue, change in bowel habits or loss of appetite needs a medical visit. For intentional loss, choose balanced diets and regular exercise.
What the numbers mean
Safe weight loss is generally 1 to 2 pounds a week, according to the CDC. Losing 5 pounds in a week is possible with a large calorie deficit or at the start of a diet, mostly from water and glycogen loss, since one pound of fat equals about 3,500 calories. Reducing carbohydrates drops water weight quickly.
Risks and when to check
Unplanned rapid weight loss, especially more than 5 percent of body weight in 6 to 12 months, can signal thyroid disease, diabetes, infection, depression or cancer. See a doctor if it happens without trying. Crash dieting raises risk of gallstones, muscle loss and nutrient deficiency.
What is a typical rate of loss
Most guidelines, including the CDC, consider 1 to 2 pounds per week a safe, sustainable rate. Losing 5 pounds in a week is possible in the first week of a diet or exercise plan, mostly from water, glycogen and food in the gut. Each gram of stored glycogen holds about 3 grams of water, so cutting carbohydrates produces a quick drop on the scale.
When it is a concern
Fast loss without trying, especially more than 5 percent of body weight in 6 to 12 months, can signal hyperthyroidism, diabetes, infection, depression, cancer or digestive disease. A drop from illness or very low calorie diets can cause gallstones, muscle loss and nutrient deficiency. Daily weight varies by 1 to 3 pounds with salt and fluids. If loss is unexplained or comes with fatigue, fever or appetite change, see a doctor. People with a history of disordered eating should seek professional support.
Based on data from the Centers for Disease Control and Prevention and the Mayo Clinic
