Doctors are prescribing new medications that help people lose weight by reducing hunger and controlling blood sugar. These drugs work really well, but they come with some hidden challenges. People taking them may lose muscle along with fat, feel sick to their stomach, or not get enough vitamins and minerals. This review looks at what happens when you take these medications and explains how eating more protein, exercising with weights, and making smart food choices can help you stay healthy while losing weight. The key message: these drugs are powerful tools, but they work best when combined with good eating habits and exercise.

The Quick Take

  • What they studied: How new weight loss medications affect your nutrition and health, and what you can do to stay healthy while taking them
  • Who participated: This is a review paper that looked at many different studies about adults taking new obesity medications. It focused on people of all ages, especially older adults and those with existing health problems
  • Key finding: These medications help people lose weight quickly, but they can cause stomach problems, muscle loss, and vitamin deficiencies if people don’t eat the right foods. Eating enough protein and exercising can prevent these problems
  • What it means for you: If you’re taking these medications, work with a doctor or nutritionist to make sure you’re eating enough protein, getting all your vitamins and minerals, and doing strength training. This helps you lose fat instead of muscle and keeps you healthy long-term

The Research Details

This is a narrative review, which means researchers read through many published studies about new weight loss medications and summarized what they found. They looked at how these drugs affect your body, what side effects people experience, and what nutrition strategies might help. The researchers focused on studies about incretin-based medications—a newer class of weight loss drugs that work by making you feel fuller and controlling your blood sugar. They examined both the benefits of these medications and the potential problems that can happen when people take them without paying attention to nutrition.

These weight loss medications are becoming very popular and are being prescribed to millions of people. It’s important to understand not just that they help you lose weight, but also what nutritional problems might happen so doctors and patients can prevent them. This review brings together information from many studies to give a complete picture of what people need to know

This is a narrative review, which means it’s based on researchers reading and summarizing other studies rather than conducting a new experiment. This type of review is good for understanding the big picture and identifying gaps in research, but it’s not as strong as a review that uses very strict methods to select studies. The information is current (published in 2025) and comes from a respected nutrition journal. However, readers should know that some of the recommendations about protein intake and exercise are based on emerging evidence rather than definitive proof

What the Results Show

The review found that new weight loss medications are very effective at helping people lose weight—sometimes 15-20% of body weight or more. These drugs also improve blood sugar control and reduce heart disease risk. However, they come with nutritional challenges that doctors and patients often don’t talk about enough. The most common problems include stomach upset, nausea, and constipation that can make it hard to eat enough food. More importantly, people often lose muscle along with fat, which can make them weaker and slower as they age. The medications work so well at reducing hunger that people might not eat enough protein or might choose low-quality foods that don’t have the vitamins and minerals their bodies need.

The review also found that these medications might change how people think about food in ways that could be harmful long-term. Some people develop unhealthy eating patterns or become too focused on food restriction. The medications can also increase the risk of vitamin B12 deficiency, which is important for nerve and brain health. For older adults, the muscle loss is especially concerning because it can lead to falls, broken bones, and loss of independence. The review suggests that while these medications reduce the amount of food people eat, they don’t automatically improve the quality of food choices—people might still eat too many processed foods that lack nutrition

Previous weight loss methods like diet and exercise alone work more slowly but don’t cause the same muscle loss problems. Older weight loss medications had different side effects. These new incretin-based drugs are more effective at weight loss than older options, but they require more attention to nutrition to avoid problems. The review suggests that combining these medications with nutrition strategies is better than using the medications alone, which is different from how they’re often prescribed today

This review looked at many studies but didn’t conduct a new experiment, so some findings are based on limited evidence. The review notes that there aren’t enough studies specifically looking at how to prevent muscle loss and nutritional deficiencies in people taking these medications. Most studies have focused on weight loss and blood sugar control rather than long-term nutrition and muscle health. The review also points out that we need more research on how these strategies work for different groups of people, especially older adults and those with eating disorders

The Bottom Line

If you’re taking these weight loss medications: (1) Eat at least 1.2-1.6 grams of protein per kilogram of body weight daily—this means if you weigh 70 kg (154 lbs), aim for 84-112 grams of protein per day. (2) Do strength training 2-3 times per week to keep your muscles strong. (3) Take a multivitamin and have your doctor check your B12, iron, and other nutrient levels regularly. (4) Eat whole foods like vegetables, fruits, lean meats, and whole grains rather than processed foods. (5) Work with a registered dietitian who understands these medications. These recommendations have moderate confidence because they’re based on good science but need more research specifically in people taking these drugs

Anyone taking these new weight loss medications should pay attention to this information. It’s especially important for people over 65, people with a history of eating disorders, people with existing vitamin deficiencies, and people with chronic diseases. If you’re considering these medications, talk to your doctor about nutrition planning before you start. People who are just trying to lose weight through diet and exercise alone don’t need to worry about these specific medication side effects, but the nutrition advice about protein and strength training is still good for everyone

Muscle loss can start happening within weeks of taking these medications, so it’s important to start strength training and eating enough protein right away. You might notice stomach problems within days. Vitamin deficiencies can develop over months, which is why regular blood tests are important. The benefits of eating more protein and exercising should become noticeable within 4-8 weeks in terms of how strong you feel. Long-term success with these medications usually takes 6-12 months to see the full picture of whether you’re maintaining muscle, staying healthy, and keeping the weight off

Want to Apply This Research?

  • Track daily protein intake (in grams) and strength training sessions. Set a goal based on your weight (aim for 1.2-1.6g per kg of body weight) and log what you eat. Also track how you feel—energy levels, muscle strength, and any stomach problems. This helps you and your doctor see if you’re getting enough nutrition
  • Use the app to plan high-protein meals and snacks before you take your medication. Set reminders to take your vitamins and minerals. Log your strength training workouts (even 20-30 minutes counts). Track any side effects like nausea so you can discuss them with your doctor. Use the app to find recipes that are high in protein and whole foods rather than processed options
  • Check in weekly on protein intake and exercise. Every month, review your energy levels and muscle strength. Every 3 months, get blood work done to check vitamin and mineral levels, especially B12, iron, and vitamin D. Use the app to share this information with your doctor or dietitian. Track your weight, but also pay attention to how your clothes fit and how strong you feel—these are better signs of health than the scale alone

This review summarizes research about weight loss medications and nutrition, but it is not medical advice. If you are taking or considering taking weight loss medications, talk to your doctor or a registered dietitian before making any changes to your diet or exercise routine. Your doctor needs to monitor your health with blood tests and check-ups while you’re taking these medications. Do not start or stop any medication without talking to your healthcare provider first. This information is especially important if you have a history of eating disorders, existing health conditions, or are taking other medications. Individual results vary, and what works for one person may not work for another.