Let’s be real: Crash diets were never the way to go. Despite ads that have historically touted promises of losing 20 pounds in a matter of days, that’s not the route to sustainable weight loss. However, it may lead you to wonder: How much weight can you lose, realistically, in a month—or even a week? 

If you’re shaping your weight loss goals by month, it’s perfectly reasonable to want to put a number behind your efforts. Here’s what experts say about the amount of weight that’s practical to shoot for, plus the risk of crash diets and losing weight too quickly. 

How much weight can you lose in a month safely?

If you’re focusing on healthy eating habits and exercising, you can expect gradual weight loss over the span of a month. 

“A realistic and sustainable rate of weight loss is about 1 to 2 pounds per week, which adds up to 4 to 8 pounds in a month,” says Arnold Breitbart, MD, a board-certified plastic surgeon. Dr. Breitbart treats patients for weight loss prior to performing body-contouring liposuction.

Patients using GLP1 medications under medical supervision might see closer to 1.5 to 3 pounds per week initially, especially if they’re also making lifestyle changes like eating healthy and exercising. (Learn more about how much weight you can lose on Ozempic here.)

“However, we always stress that slow and steady is the most successful path,” says Dr. Breitbart. “The goal should not be to lose weight fast—it’s to lose weight for good and to do it in a way your body can maintain.”

Why crash diets can backfire on your weight loss goals

Many fad diets emphasize reducing calories to lose a significant amount of weight each week or month. But this can lead to hormonal changes that actually stimulate appetite and make you crave higher-calorie foods. Crash diets can also cut out entire food groups like wheat or dairy that contain nutrients needed for good health, per the American Heart Association.

“When people deprive their bodies, they often lose water and muscle—not fat.” —Arnold Breitbart, MD

“Crash diets are one of the quickest paths to metabolic confusion, nutritional deficiency and inevitable rebound weight gain,” cautions Dr. Breitbart. “When people deprive their bodies with extreme calorie cuts or eliminate entire food groups, they often lose water and muscle—not fat.”

This makes long-term results more difficult to achieve and maintain. 

“In our practice, we often see patients who come in after trying multiple crash diets who are frustrated and metabolically drained,” adds Dr. Breitbart. “Managing expectations and focusing on sustainable strategies leads to much better outcomes.” 

Health risks of losing weight too quickly

Other risks of crash diets include:

• Gallstones: These can appear as a result of very rapid weight loss, likely due to changes in fat metabolism. Gallstones can cause severe pain and illness.
• Loss of muscle and bone: You don’t just lose fat when you lose weight. Working with a medical professional can help you lose fat without losing bone tissue or muscle, which is associated with poor health, especially as we age. 
• The rebound effect: When your body thinks you’re starving because you’re not eating enough calories, it slows down your metabolism. This can make it harder to lose weight and more likely that you’ll regain weight very quickly when you start adding more calories back into your diet. Hence, the frustrating yo-yo effect many crash dieters experience. 

The best way to lose weight each month, according to doctors

The best weight loss plans combine your doctor’s medical guidance with practical lifestyle shifts. “I recommend patients commit to at least two to three strength training sessions a week, which preserves lean muscle during fat loss and improves long-term metabolic health,” says Dr. Breitbart.

He also emphasizes protein-rich diets with plenty of fiber from vegetables, plus limiting simple sugars and processed foods. Hydration and sleep often get overlooked when it comes to losing weight, but they also play key roles in appetite regulation.