After decades of avoiding mirrors, I was finally able to look at myself in one. As a matter of fact, after losing 85 pounds over a year with the help of GLP-1 medication, I almost couldn’t stop looking at myself.
And I wasn’t just looking. I was scrutinizing, checking out every inch of my rapidly changing face and beginning to recognize myself again — the self I was before putting on so much weight over the years.
Then, wait … what’s this? Hair loss. Not just a few strands in the drain after a shower. I’m talking about a quickly widening part that was turning into a long bald spot in the middle of my head. Add that to the fatigue, weakened muscles, and what I politely describe as “bathroom woes,” and I was questioning whether it was even worth it.
But after finally being categorized as “normal” weight rather than “obese” or “morbidly obese” and, more importantly, reducing my A1c level from 13 to 5.4 and getting my diabetes under control, I realized it was more than worth it. It saved my life.
The “downside” of losing weight quickly — whether from medication, surgery, or diet and exercise —can affect your energy, strength, digestion, and long-term success. And it can be incredibly frustrating.
But understanding these risks can help you protect your health while working toward your goals. Here, bariatric dietitian Chelsea Hoover, assistant professor in the Department of Nutrition Sciences and Health Behavior at UTMB, breaks down the downsides and what you can do to mitigate them.
Muscle loss and fatigue
Not all weight loss is fat. In fact, generally around 25% of weight lost comes from muscle, Hoover said. Muscle is essential for strength, energy, and injury prevention. Losing too much can lead to fatigue or low energy, reduced strength and stamina, a higher risk of injury, and difficulty maintaining weight loss.
“Since people are generally losing weight to try to achieve improved health outcomes, minimizing the loss of muscle during the weight loss process is key,” she said.
Dehydration and constipation
Rapid weight loss often goes hand in hand with reduced appetite and lower fluid intake. Some weight-loss therapies may even dull thirst cues. If you’re feeling dizzy and/or overly tired, have muscle cramps, a fast heart rate, and constipation, you’re most likely dehydrated.
“Constipation itself isn’t directly caused by the weight loss, but is more often a side effect of dehydration, GLP-1 medications, and/or a reduction in fiber intake,” Hoover said. “Many people are surprised to learn that the dramatic drop on the scale in the first week of a new plan is often not fat. When people lose weight very quickly after first starting a diet, particularly keto, it’s usually related to fluid loss rather than fat loss.”
Vitamin and mineral deficiencies
Very low-calorie diets can make it hard to get enough vitamins and minerals. Rapid weight loss is usually caused by a drastic reduction in energy intake, which can lead to deficiencies in vitamin D, B vitamins, and iron.
“Hair thinning or shedding can also be alarming, but it’s more of a side effect of protein or micronutrient inadequacies not directly caused by the weight loss,” Hoover said.
But how to handle all this? The goal isn’t to avoid weight loss, it’s to approach it in a way that supports your body rather than stresses it.
Eat enough protein
Protein plays a major role in preserving muscle while losing fat. A common recommendation is 1 to 1.5 grams of protein per kilogram of body weight (70 to 100 grams for a 150-pound person, for example) per day, divided across meals in 20- to 30-gram increments.
Some of the best sources include fish and seafood, poultry and lean meats, eggs and low-fat dairy, and beans, lentils, tofu, and other plant-based proteins.
“Protein shakes can help if food intake is low, but whole foods are usually preferred because they provide additional nutrients,” Hoover said.
Stay active
Exercise supports heart health and muscle maintenance. The Physical Activity Guidelines for Americans recommend 150 to 300 minutes of moderate aerobic activity a week and muscle-strengthening activities twice a week.
“Aerobic activity helps with heart health and weight maintenance, while strength training is most beneficial for stimulating muscle maintenance and growth,” Hoover said. “It’s also worth remembering that muscle repair requires adequate dietary protein.”
Focus on hydration and fiber
Aim for at least 64 ounces of water or other clear, sugar-free, caffeine-free liquids daily, unless your health care provider advises differently, Hoover said. For digestive health, gradually increase fiber to 25 to 30 grams per day from foods such as berries and other fruits, vegetables like broccoli and Brussels sprouts, whole grains such as oats and quinoa, beans, and lentils.
Increasing fiber slowly can help prevent bloating and discomfort.
Consider a multivitamin
If you’re eating very little, skipping food groups, taking GLP-1 medications, or recovering from weight-loss surgery, a daily multivitamin may be necessary to help prevent deficiencies.
However, “a balanced diet remains the best foundation whenever possible,” Hoover said.
If you’re already experiencing side effects, she said, consider making an appointment with a registered dietitian nutritionist or your health care provider. Many insurance plans cover nutrition counseling, especially for patients using weight-loss medications or preparing for bariatric surgery.
“In many cases, small changes in hydration, protein intake, or vitamin support can significantly improve symptoms,” she said.
Another growing concern, particularly with medication-assisted weight loss, is regaining weight after stopping treatment. Research suggests that the more drastic the weight loss, the more quickly it can pile back on if you don’t change your lifestyle and attitude toward nutrition and exercise.
Hoover’s advice? Learn as you go.
“The most successful long-term results usually come from gradual, consistent changes in eating patterns, movement, and daily routines,” she said. “Medications and surgery can be valuable tools, but they work best when paired with sustainable habits that support health well beyond the number on the scale.”
Looking for guidance on your journey toward a healthy weight? Start by making an appointment with a primary care provider.