According to most recent statistics, nearly 50% of Americans are trying to lose weight in any given year. Of those, nearly 20% use weight loss drugs to help them ‘trim the fat’.
Over the past year, there’s been a major uptick in interest surrounding weight loss drugs. This is mainly because ‘Hollywood’s elite’ have flooded social media with photos of their rapid, and often unhealthy, weight loss by using newer, injectable weight loss drugs. In fact, almost 50% of Americans are now interested in using weight loss drugs! Not only has this increased the demand for these drugs, but it has also drastically inflated their prices.
The FDA has approved certain weight loss medications for people with a Body Mass Index (BMI) of 30 or higher or for those with a BMI of 27 or higher who also have a weight-related condition, such as type 2 diabetes or high blood pressure. There are several classes of weight loss medications available, and all of them require a prescription and physician supervision. In this blog, I will fill you in on the main classes of weight loss drugs currently available, how they work, potential side effects, and the success rates of each.
But here’s the bottom line…
…lifestyle will always trump weight loss drugs and/or fad diets. Weight loss medications are not meant to be long-term solutions but rather short-term tools which may improve chances of long- term success. As you’ll read below, the majority of people regain all or a portion of their lost weight once they stop using the medication. And don’t forget, based on my previous blogs, there are many different factors that affect body weight other than diet and exercise. If these other hidden factors are not identified and corrected, no weight loss drug will help you lose much weight and/or keep it off.Here's an overview of the major categories of currently available weight loss medications:
• Medications that suppress appetite
o Phentermine
o Qsymia
o Contrave
o Didrex
• Medications that prevent dietary fat absorption
o Orlistat
• Medications that affect insulin and blood sugar
o Metformin
o Semaglutide (Ozempic, Wegovy)
o Liraglutide (Saxenda, Victoza)
Appetite Suppressants
These drugs work by affecting brain chemicals that help regulate hunger. When taken, they make a person eat less and feel full sooner.
1. Phentermine (Adipex-P, Lomaira):
o A stimulant drug that suppresses appetite by affecting chemicals in the brain and intestinal tract. This medication is approved for short-term use only (up to 12 weeks) because of dependency and potential side effects which include high blood pressure, heart arrhythmias, GI upset, insomnia, anxiety, and glaucoma.
o Some physicians may prescribe it for a longer term so long as it’s taken only several times a week.
o Clinical trials show that individuals using phentermine typically experience 5- 10% body weight loss over a 12-week period.
o This drug does not work well for all people. One-third of people who take phentermine only lose l
ess than 3 percent of their weight within the first 3 months of starting the drug.
2. Phentermine-Topiramate (Qsymia):
o This is a combination of phentermine and topiramate (Topamax), an anticonvulsant drug also used to treat seizures and migraine headaches. It works by reducing cravings and feelings of hunger.o It’s designed for extended use in combination with a healthy diet and exercise. Studies have shown sustained weight loss over one to two years of treatment.
o If patients don’t lose at least 5% of their body weight) after 12 weeks on the highest dose, the medication is typically discontinued.
o A loss of
10% to 11% of total body weight after a year of taking the max dose (15mg phentermine/92mg topiramate) of Qsymia has been reported, according to a study published in the
Annals of Pharmacotherapy. If the standard dose is taken (7.5mg/46mg), people can expect to lose about 8% of their total body weight after one year.
o Coupled with the potential side effects of Phentermine, the side effects of Topiramate include hair loss, serious skin reactions, GI upset, memory loss, and serious mood changes.
3. Bupropion-Naltrexone (Contrave)
o Bupropion is an antidepressant that can reduce appetite and cravings. Naltrexone is often used to treat addiction. Together, they affect hunger and reward pathways in the brain, helping reduce food cravings.
o Patients taking Contrave can lose an average of 5-10% of their body weight over a one year period.
o Side Effects include GI upset (nausea, vomiting, diarrhea), insomnia, headaches, increased blood pressure and heart rate, mood changes, and seizures.
4. Benzphetamine (Didrex) and Diethylpropion:
o Both are FDA-approved for short-term treatment of obesity and are typically prescribed for only a few weeks (because of side effects and dependency).
o They work by reducing appetite by stimulating the central nervous system.
o Side Effects: Common side effects include insomnia, dry mouth, and nervousness. It can also increase heart rate and blood pressure, so it’s contraindicated in people with certain heart conditions.
o These drugs are not suitable for everyone. They require careful monitoring by a healthcare provider due to potential side effects and interactions with other medications.
Fat Absorption Inhibitors
These medications prevent the absorption of dietary fat in the intestines thereby reducing the absorption of extra calories.1. Orlistat (Alli, Xenical):
o Available in both prescription strength (Xenical) and over-the-counter (Alli).
o These drugs block about 25% of the fat you eat from being absorbed by your digestive system.
o These drugs can be taken long term (over one year), but labs need to be regularly monitored, especially the levels of fat soluble vitamins (A,E, D, and K).
o Over a one year period, people taking orlistat in combination with a low calorie diet show a reduction of
5 to 10 pounds over the weight decrease with placebo.
o 35-50% of people regain weight within a year after stopping this drug if they don't maintain healthy lifestyle changes.
o Side effects are mainly gastrointestinal and include Oily spotting on underwear, excessive intestinal gas, urgent bowel movements, fatty or oily stools, and an increase in the number of daily bowel movements.
Medications Affecting Insulin & Blood Sugar
1. Metformin:
o Primarily used for the treatment of pre-diabetes and type 2 diabetes.
o Studies suggest that individuals taking metformin may lose 2-5% of their body weight over six to twelve months. While the weight loss is generally moderate, it can be sustained when combined with permanent lifestyle changes.
o Side effects are mainly gastrointestinal (nausea, bloating, diarrhea). A metallic taste in the mouth and B12 deficiency are also common.
2. GLP-1 Receptor Agonists (newest, injectable medications):
o This class of medications was originally developed for treating type 2 diabetes.
More recently, they have become widely used for weight loss due to their effects on appetite regulation and insulin sensitivity.
o These medications result in more weight loss (15-20%) than oral medications (5- 10%).
o These drugs reduce body weight by slowing stomach emptying, reducing hunger signals, and improving the body’s ability to use insulin.
o These drugs are typically not covered by health insurance and range from $1000 to $1500 per month.o There are several GLP-1 agonist drugs on the market, but only TWO are approved for weight loss:
▪ Semaglutide (Wegovy, Ozempic)
▪ Requires weekly injections.
▪ Patients experience an average weight loss of about 12-15% of their body weight over a year as long as they keep using the medication.
▪ Patients regain about two-thirds of the weight they lost within a year after stopping the medication.
▪ Liraglutide (Saxenda, Victoza)
▪ Requires daily injections.
▪ On average, studies have shown that individuals using Saxenda can achieve a weight loss of
around 5-10% of their initial body weight after one year of use.
▪ Patients regain about 50% of their weight within a year of stopping the drug.
o Side Effects include GI upset (nausea, vomiting, diarrhea, constipation), increased heart rate, high blood pressure, memory problems, pancreatitis, gall bladder disease, kidney problems, mood issues (including suicidal thoughts), and low blood sugar.
Regaining Weight After Stopping Weight Loss Drugs
It is the norm rather than the exception when it comes to regaining weight after stopping weight loss drugs. In general, studies suggest that most people regain about 50% the weight they lost within two years, and over 80% regain it within five years. This is typically because people resort to their previous diet and exercise habits once they stop the medications.
This is NOT always the case with the GLP-1 receptor agonist medications, Wegovy and Ozempic. Emerging research has found that some patients regain weight after stopping these drugs even if they continue a healthy lifestyle.
Researchers are still trying to find out exactly why this happens. So far, they’ve discovered that once these medications are stopped, weight gain occurs through these mechanisms:
1. Rebound hormonal imbalances, primarily with Ghrelin and Leptin, two key appetite regulating hormones.
2. Reduced the ability of the pancreas to make insulin.3. Inability of the brain to regulate hunger signals
4. Change gut microbial balance (which has a significant impact on body weight and food cravings).
This is an important consideration for people to keep in mind before they try these medications for weight loss. It’s very possible that life-long therapy will be required for weight loss to be maintained.
