GLP-1 medications have changed the conversation around weight loss, offering many patients an effective tool for improving their health. But when the number on the scale keeps dropping, more weight is not necessarily better.
If you’re taking GLP-1 medications, keep in mind: Healthy weight loss is about more than reaching a particular number. Losing weight too quickly or losing more than intended can affect muscle mass, nutrition, and overall health.
Dr. Krystal Tamura, chief medical officer of CommonSpirit St. Anthony North Hospital and a board-certified obesity medicine physician, has treated weight loss patients for years. She developed a comprehensive weight-loss program that incorporates medical, nutritional, and behavioral health care.
“Everyone’s weight loss journey on GLP-1 medications is different,” Dr. Tamura said. “It can depend on their starting weight, dose of medication, and other co-morbidities.”
When Does Weight Loss Become Too Much?
There is no single amount of weight loss that automatically means a person has gone too far. Dr. Tamura said you can generally expect to lose about 10% to 25% of your total body weight, depending on the medication you are taking. Losing more can still be appropriate for some people, too.
Concern arises, however, if your BMI falls into the underweight range, below 18.5. BMI refers to “body mass index,” a measure of body fat based on height and weight that can help physicians and medical providers understand your health.
However, the amount of weight you lose is only part of the picture. Because GLP-1 medications can significantly reduce appetite, some people may struggle to eat enough calories or protein. That can result in sarcopenia, the loss of muscle mass and strength.
Fatigue, weakness, and dizziness can be warning signs. According to Dr. Tamura, these symptoms can be related to dehydration, nutritional deficiencies, or muscle loss and should be discussed with a health care provider.
Severe gastrointestinal side effects can create additional concerns. Vomiting and diarrhea can contribute to inappropriate weight loss while also increasing the risk of electrolyte and nutritional problems.
Losing Weight Quickly Can Have Consequences
Rapid weight loss may sound appealing, but the body needs adequate nutrition to maintain muscle, bones and other essential functions.
“In weight loss, ‘slow and steady wins the race,’” Dr. Tamura said.
She generally recommends losing about 0.5 to 2 pounds per week. Losing more than that does not necessarily mean something is wrong, but it can increase the likelihood of problems such as muscle loss.
Other potential consequences of losing too much weight or losing it too quickly include hair loss, gallbladder stones, dehydration, and osteoporosis, or low bone mass.
One particularly important consideration is calorie intake. Dr. Tamura said consistently eating fewer than 1,000 calories a day because of reduced appetite can severely decrease metabolism, reduce muscle mass, and increase the risk of deficiencies in nutrients, such as iron, vitamin B12, folate, and vitamin D.
Protecting Muscle During Weight Loss
Preserving muscle should be a priority throughout GLP-1 treatment. Dr. Tamura recommends targeting 1 to 1.2 grams of protein per kilogram of body weight each day, along with at least 1,200 to 1,500 calories.
High-fiber foods (think fruits, vegetables, and whole grains) can help provide you with essential nutrients. Fiber can also help combat constipation, a common side effect of GLP-1 medications.
Exercise matters, too. While cardiovascular exercise supports heart and lung health, strength training is particularly important for maintaining muscle mass and strength.
“Strength training is the real must for maintaining muscle mass and strength,” Dr. Tamura said.
She recommends strength training twice a week, using options such as body-weight exercises, machines, dumbbells or resistance bands.
You can also work with your health care team to monitor changes in body composition. Dr. Tamura said special scales can measure body fat and muscle percentage, providing information beyond what the scale alone can show.
When to Talk with Your Provider
If you are losing weight faster than expected, struggling to eat enough, or experiencing concerning side effects, you should talk with your health care provider. Treatment adjustments may be appropriate, but the right approach depends on why your weight loss is happening.
If severe side effects such as vomiting or diarrhea are contributing to weight loss, a provider may consider lowering the medication dose or changing medications. If you are tolerating the medication but continue to lose weight at a high dose, your provider may gradually reduce it until you reach a maintenance level.
If you’re already taking the lowest dose and continue to lose weight, switching from an injectable medication to a less-potent oral formulation may be another option.
The goal is not necessarily to stop treatment. Instead, your doctor may adjust the plan to help you maintain a healthy weight while getting adequate nutrition.
Health, Not Just the Number
Dr. Tamura said one of the most common scenarios she sees is patients who continue trying to push their weight lower because of an “ideal body weight or image.”
That mindset can make it easy to overlook the health improvements that have already occurred.
“I like to emphasize how far they have come from their starting weight and that a 10-20% weight loss has immense health implications with reversing and preventing chronic medical issues,” Dr. Tamura said.
Social media and celebrity culture can also create unrealistic expectations about what you should look like, she said. That can shift the focus away from health and toward continually lowering the number on the scale.
“A 10-20% weight loss may not seem like ‘enough’ to them, but our main focus should be on improving a patient’s health, not just a number on the scale,” Dr. Tamura said.
If you’re taking GLP-1 medications, sustainable weight loss should include adequate calories and protein, muscle-preserving exercise, and regular communication with your health care provider. Weight is one measure of progress, but it is not the only one.
“I would encourage all patients to work closely with their health care provider to monitor weight loss and engage in shared-decision making around when to modify the treatment plan and maintain a healthy weight,” Dr. Tamura said.
