Weight Loss Drugs and Nutrition
By Susan P. Cohen, MA, RDN, CDN
The latest numbers show that 73 percent of adults in the U.S. are overweight or obese and almost half are trying to lose weight (1,2). Losing weight and keeping it off is not easy. Making healthy lifestyle changes, and maintaining them for weeks, months, and years can be very difficult (3).
Choosing more nutritious foods in optimal amounts and increasing physical activity are wise moves for just about everyone’s physical and mental health. Losing 5-10 percent of weight helps to lower triglycerides, blood pressure, and blood sugar levels (4). However, even after implementing a healthier lifestyle, there may be a need to further reduce weight (3).
The good news is that there are a number of weight loss medications approved by the FDA for long-term use. They’re also known as “anti-obesity medications” (AOMs) (5). These medications can provide some extra help. They’re meant to be used alongside healthy eating habits and regular physical activity because these medications don’t work on their own (3,4,5,6).
Most of these weight loss medications require a prescription from a physician. They are mainly for people who have already tried to lose weight through nutrition and exercise, and either have a BMI of at least 30, or have a BMI of at least 27 plus a health condition like diabetes or high blood pressure for which there would be a great health benefit to lose additional weight (5,7).
The purpose of these drugs is to help manage weight while already eating a nutritious diet and doing regular physical activity (7). Combining one of these medications with a healthy lifestyle will help to boost weight loss by 3-12 percent more than diet and lifestyle changes alone (4,7). They are not recommended for anyone who is pregnant, breastfeeding, or trying to get pregnant (7).
This article briefly discusses some of the pros and cons of taking these drugs, such as their benefits, how they work, their side effects, as well as some important nutrition strategies you need to know when taking one of these medications.
What are the weight loss drugs and how do they work?
There is a wide selection of long-term weight loss drugs to choose from (5). There isn’t one that is going to be the most effective for everybody and it’s not possible to know for sure which would work best for you or how effective it will be (5). Start with a conversation with your doctor to help decide where to start. Based on your current health status, other medications and supplements you’re taking, and your family history, along with how expensive the medications are and their associated side effects, you and your doctor can decide next steps (4,5).
According to the Obesity Medicine Association, “All weight loss medications work best in the context of a healthy eating plan and exercise” (5). There are several different ways that these weight loss drugs work. Most help you to feel less hungry, to feel fuller faster, and/or to reduce cravings (5,7). They do this by interacting with hormones (e.g., leptin, ghrelin), neurotransmitters (e.g., GABA, serotonin), and peptides (e.g., GLP-1) found in the brain, gut, and fat tissue (5,6).
This physiological strategy works because when you feel less hungry, fuller faster, and have fewer cravings, it becomes easier to consume fewer calories, resulting in weight loss (6).
Note: Orlistat works differently because it impacts the way the digestive system absorbs fat (7).
Semaglutide, tirzepatide, and liraglutide
Semaglutide and tirzepatide are weekly injections of “glucagon-like peptide-1 (GLP-1) and GIP receptor agonists” (4,5). They work by targeting areas of the brain that regulate appetite and food intake (4,5). The dosages start low and are gradually increased over the course of 16-20 weeks (5). The reason for starting with a lower dosage is to reduce side effects (e.g., gut issues, headaches, dizziness, and fatigue) (5). Liraglutide is a daily injection that acts on gut hormones to help feel fuller faster and to decrease hunger (5).
Bupropion-naltrexone
These tablets are a combination of two different medications including an antidepressant that can help weight loss and an opioid receptor antagonist that helps with alcohol and drug dependence (4,5). Taking these together can impact the pleasure-reward area of the brain and help to feel fuller faster and decrease appetite and cravings (4,5).
Phentermine and phentermine-topiramate
Phentermine is the oldest and most commonly used weight loss medication(5). Phentermine is a pill that works by reducing appetite to make you less hungry (4). When combined with topiramate (used to help with seizures and migraines), they work together to further reduce appetite and cravings (5).
Setmelanotide
Setmelanotide is a daily shot that is specifically for people who have a certain rare inherited disease (e.g., Pro-opiomelanocortin deficiency, proprotein subtilisin-kexin type 1 deficiency, or leptin receptor deficiency) (7). While it doesn’t treat the underlying genetic condition, setmelanotide can help with weight loss by helping to feel fuller, reduce appetite, and help the body burn more calories at rest (7).
Orlistat
Orlistat is different from the rest of the long-term weight loss medications. It’s available by prescription and a reduced strength version is non-prescription (7). Orlistat capsules are taken with meals and work to reduce the body’s ability to break down and absorb fat from foods and drinks by about 30 percent (8). It does this by preventing the enzymes that digest fat from working (5). This means that, instead of absorbing the calories from fats, they continue traveling through the digestive system and are eventually excreted.
What are some common side effects of weight loss medications?
While these medications are safe when used as directed, there are some side effects to be aware of (6). Most of the side effects are mild and many resolve with continued use (4). The most common side effects affect the digestive system, such as nausea, constipation, and diarrhea (7,8). Some people may also experience dry mouth, abdominal pain, vomiting, headaches, dizziness, nervousness, insomnia, and tiredness (5,7,8). As with any medication, there is a small chance of serious side effects (7).
With orlistat, the unabsorbed fats going through the digestive tract undigested is why some of the common side effects include abdominal pain, loose stools, and passing more gas (4,7).
Another common experience with anti-obesity medications is regaining some of the lost weight after stopping their use (4,5,7,8). This is the body’s natural metabolic response to weight loss—including weight loss with or without medications (5). This is partly due to a decrease in resting metabolic rate, as well as impacts to the hormones that make you feel hungry and full (5). According to the Mayo Clinic, “practicing healthy lifestyle habits may help limit weight gain” (7).
It’s important to stay in touch with your doctor when taking any anti-obesity medication, and to contact them if you experience any negative effects (6). You may need to follow-up regularly to share how you’re feeling, what side effects you’re experiencing, and how much weight you’ve lost so far (7). These can help you and your doctor determine whether the medication is working for you, whether to switch to another one, and when to stop taking it (7).
What nutrition advice is essential when taking weight loss medications?
The most important thing to consider when taking any of these weight loss medications is to maintain a healthful eating plan. This means that you’re getting all of the essential nutrients and eating the optimal quantities of food to help you reach your weight loss goals. Avoid weight loss programs that have too many unrealistic promises (1).
According to the National Institute of Diabetes and Digestive and Kidney Diseases, a safe and successful weight loss program includes “a healthy, reduced-calorie eating and drinking plan, a plan for increasing physical activity if appropriate, guidance and support for adopting these lifestyle habits, and a plan for keeping the weight off” (1).
The purpose of a good weight loss program is to set realistic weight loss goals, promote healthy long-term behaviors, and provide techniques to track progress and overcome barriers (1). Ideally, all of the elements listed above would be tailored to your specific situation by a healthcare professional such as a registered dietitian nutritionist.
While there is no one-size-fits-all weight loss program, there are some important nutritional guidelines to keep in mind when working toward losing weight:
A realistic weight loss goal is to lose about one pound per week (9)
Focus on highly nutritious, filling, fiber-rich foods like fruits, vegetables, and whole grains (9)
When it comes to meat and dairy, choose leaner cuts and lower fat options (9)
Minimize less nutritious foods (e.g., fried foods, or those high in sugar or salt) (8,9)
Keep portion sizes in check (8,9)
Choose water as your go-to beverage (9)
Increase the amount of physical activity you do on a regular basis (9)
Because orlistat works to prevent fat digestion, there are a few additional nutrition recommendations specific to this medication.
Reducing the absorption of fats can also reduce the absorption of some essential vitamins and minerals. Talk to your trusted healthcare provider about including a multivitamin or other supplement (8).
Many of the gastrointestinal side effects can be reduced by pairing orlistat with a diet that’s lower in fat (5).
Final thoughts
According to the Mayo Clinic, “Weight-loss drugs aren't an easy answer to weight loss. But they may help you make the lifestyle changes that you need to practice to lose weight and improve your health” (7).
Do you need help making lifestyle changes that can lead to sustainable weight loss with or without weight loss medications? As a registered dietitian nutritionist, I’d love to help.
Want support to create a nutrition and lifestyle program to make losing weight easier? Need personalized recommendations for recipes, meal plans, and other ways to ensure you’re getting all of the necessary nutrients in the optimal amount of food to reach your health goals? Ready to start working with a professional who is invested in seeing you thrive, despite weight management challenges? Request an appointment with me today.
References
National Institute of Diabetes and Digestive and Kidney Diseases. (2024, February). Choosing a Safe & Successful Weight-loss Program. U.S. Department of Health and Human Services, National Institutes of Health. https://www.niddk.nih.gov/health-information/weight-management/choosing-a-safe-successful-weight-loss-program
National Center for Health Statistics. (2018, July). Attempts to Lose Weight Among Adults in the United States, 2013–2016. Centers for Disease Control and Prevention. https://www.cdc.gov/nchs/products/databriefs/db313.htm
Mayo Clinic (2023, November 1). Weight loss basics. https://www.mayoclinic.org/healthy-lifestyle/weight-loss/basics/weightloss-basics/hlv-20049483
National Institute of Diabetes and Digestive and Kidney Diseases. (2023, March). Prescription Medications to Treat Overweight & Obesity. U.S. Department of Health and Human Services, National Institutes of Health. https://www.niddk.nih.gov/health-information/weight-management/prescription-medications-treat-overweight-obesity
Obesity Medicine. (2024, January 26). Top Weight Loss Medications. https://obesitymedicine.org/blog/weight-loss-medications/
Cleveland Clinic. (2023, November 20). Appetite Suppressants. https://my.clevelandclinic.org/health/treatments/9463-appetite-suppressants
Mayo Clinic. (2022, October 29). Prescription weight-loss drugs. https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/weight-loss-drugs/art-20044832
Medline Plus. (2023, July 8) Weight-loss medicines. U.S. Department of Health and Human Services, National Institutes of Health. https://medlineplus.gov/ency/patientinstructions/000346.htm
Johns Hopkins Medicine. (n.d.). Medical Nutrition Therapy for Weight Loss. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/medical-nutrition-therapy-for-weight-loss