Almost her entire life, 56-year-old Jennifer Kirtley felt so consumed by food thoughts that immediately after breakfast, she would ponder her lunch menu.

Recently, though, Kirtley went almost all day without eating, a noticeable behavior change coming only 3½ months after starting Wegovy, a popular weight-loss medication. “It’s mind-blowing that I have to remember to eat,” said Kirtley of Lake Worth Beach. “But when I am eating less amount of food, I know that I have to pay attention to what I am eating and make sure I am getting nutrients.”

Kirtley started at 328 pounds on April 1 and has lost 38 by taking the weight-loss medication under a doctor’s supervision. She follows a carefully researched diet heavy on lean protein, vegetables and lots of water.

“To avoid losing muscle mass, I focus on the protein, not on calories,” she said.

GLP-1 drugs such as Wegovy, Ozempic and Mounjaro have emerged as a game-changer for weight loss, slowing digestion and increasing how satiated you feel after eating. But South Florida dietitians caution that taking weight-loss drugs can be risky if you don’t have the right diet. Everything from your bones to your muscles can atrophy as you shed pounds too quickly. They guide patients on how to eat while on medications without causing their body harm.

“If someone does not know how to eat on these medications, they may be exchanging one problem for another,” said Lillian Craggs-Dino, a licensed dietician and support group coordinator for the Bariatric and Metabolic Institute at Cleveland Clinic Florida. “It’s easy to become vitamin deficient.”

Jennifer Kirtley, of Lake Worth Beach, started using weight-loss medication Wegovy in early April and has so far lost 38 pounds. (Carline Jean/South Florida Sun Sentinel)

The side effects are challenging

Ten GLP-1 drugs, including a class of medications called semaglutides, are FDA-approved to treat either type 2 diabetes or weight loss. Most are given by self-injection and work by regulating insulin production and lowering blood sugar levels. The most common side effects are gastrointestinal symptoms including nausea, vomiting, diarrhea, and constipation. Dietitians say the symptoms often can be managed: Diarrhea by drinking plenty of water and avoiding dairy products and high-fiber foods, and constipation by eating more fiber and drinking plenty of water.

“It may not be the drugs, it may be your diet causing the nausea or constipation. Maybe somone is eating too fast or picking the wrong foods,” Craggs-Dino said.

At Cleveland Clinic Weston, Craggs-Dino does a full assessment before someone starts weight-loss drugs to discover whether a patient has vitamin deficiencies, to learn their lifestyle habits and to find out their food allergies, likes and dislikes. She then creates an eating plan

“Medications will help with behavior because you will feel full, but you still have to eat balanced meals with lean protein, fat, whole grains and vitamins,” she said. “Some people are not hungry and don’t eat. If you don’t eat, you are not nourishing your body and you are losing muscle mass along with fat.”

Some people need vitamin supplements, and others need a higher amount of “good fat,” she said.

Losing weight rapidly without a proper diet and exercise can decrease bone density, and lower your resting metabolic rate which can lead to sarcopenia — the gradual loss of muscle mass, strength, and function that makes it hard to do daily activities like walking up stairs. Dietitians say ideally anyone on these medications should consume about 25-30 grams of protein per meal to preserve muscle.

Kirtley says she has tried all kinds of diets and watched her weight fluctuate, while she remained obese. Her eating habits had included regular trips to Dunkin Donuts and Popeye’s. But that’s in the past. She started on a low dose of Wegovy in April and plans to modify her diet further as she ramps up. She tracks her water intake and her protein consumption with an app on her phone, and allows herself protein shakes and bars.

“I knew going in I wanted to change my diet,” she said. “My hope going in was that this will help me make better choices about what I am eating, and it has.”

What to know before you self-inject

Although the internet is filled with photos of people shedding pounds on semaglutide medication, taking weight-loss drugs without any education is a mistake, dietitians say. The medications are designed to be used in combination with a healthy diet and exercise.

“Education is a critical piece that many people are missing,” said Amy Kimberlain, registered dietitian with the Miami Cardiac & Vascular Institute Cardiometabolic Clinic at Baptist Health.

“You have to understand how the medications work, what’s happening to your digestion and how to modify what and when you eat,” she said.  “You want to mitigate the side effects that could be caused by what you are eating.”

Since you are not counting calories, you should stack your plate  with nurtrient-rich foods, even when you are in maintence mode, she said. She recommends high-quality protein sources such as fish, chicken, eggs, tofu, tempeh, yogurt, cheese, and seafood. Food that should be avoided include pastries, sodas, processed foods, fatty cuts of meat, and foods high in sodium like pickles and deli meats. Fats and carbohydrates can be added into your diet eventually.

Surgical weight loss expert Dr. Christopher Thompson said some people aren’t a good candidate for weight-loss medications, even with the right diet. Thompson, a Harvard medical professor and founder of Bariendo, recommends having your bone and muscle density checked before starting on them. If your numbers are low, weight-loss surgery may be a better option, he said. Thompson performs a unique endoscopic stomach-tightening procedure for weight loss. However, he also prescribes medications, noting that patients who take them need a game plan that includes resistence training and long-term eating modifcations.

“If you start this medication, intend to be on it the rest of your life,” he said. Even after reaching a weight-loss goal, research shows that most people will need to stay on the medication indefinitely, likely at low doses. “Those who get off find weight regain is typically faster than the time it takes people to lose the weight in the first place,” he said. “It will come back with a vengence, and quickly.”

Navigating the popularity and cost

Ozempic, originally intended for Type 2 diabetes, caught on for weight loss in 2023. With its popularity, the U.S. Food and Drug Administration approved a similar medication, Wegovy, for chronic weight management. The insatiable demand saw Mounjaro (tirzepatide) arrive at the end of 2023, and now a newer, reportedly more effective drug called retatrutide is in the pipeline. The challenges with these medications in South Florida and nationwide are cost and availabiity. In South Florida, everyone from chiropracters to MedSpas to virtual doctors are prescribing them. The cost can be prohibitive — as much as $1,000 or more a month — and finding needed doses can be difficult.

But compounding pharmacies are stepping in, making their own versions of semaglutide and tirzepatide drugs at lower costs and varied dosages.

That’s the path Martin Katz, 78, is taking. He said he is using a compounding pharmacy to make doses of tirzepatide at lower prices because Medicare doesn’t cover it for obesity. He relies on dietitian Craggs-Dino from Cleveland Clinic Weston to guide his diet. Five years ago, the Coral Springs tax accountant had bariatric surgery for weight loss, and dropped 85 pounds. But by January 2024, he had gained back what he lost and wanted to try Wegovy. In the last six months on the medication, Katz has gone from 270 lbs to 230 lbs, dropping 40 pounds and two pants sizes.

Breakfast is a cottage cheese cup and cheese stick, he says. Lunch or dinner might be a small piece of chicken or fish and vegetables. “My appetite is gone so I don’t eat four slices of pizza anymore,” he said. Katz says he also lost his desire for snacking and cut out his daily six cups of coffee. “I changed my drinking and eating habits.”

Katz said he manages his own dosing, having increased in small amounts four times already.

This time around, he thinks he can maintain the weight loss.

“People have to realize this isn’t a quick fix,” he said. “It takes a commitment on your part to change your ways.”

Sun Sentinel health reporter Cindy Goodman can be reached at cgoodman@sunsentinel.com.