From the Guidelines
The most effective weight loss supplement currently available is prescription medication such as semaglutide (Wegovy) or tirzepatide (Zepbound). These GLP-1 receptor agonists have demonstrated significant weight loss results of 15-20% of body weight when used as prescribed, typically through weekly self-injections 1. The standard regimen involves starting at a low dose and gradually increasing over several months to minimize side effects like nausea and digestive issues. These medications work by mimicking hormones that regulate appetite and blood sugar, making you feel fuller longer and reducing hunger signals to the brain. They also slow stomach emptying, which helps control food intake. However, these are prescription medications requiring medical supervision, not over-the-counter supplements.
Among non-prescription options, there is limited scientific evidence supporting effectiveness of supplements like green tea extract, caffeine, or fiber supplements, which show only modest effects at best 1. For sustainable weight loss, any supplement should be combined with calorie reduction and increased physical activity, as no supplement alone creates significant weight loss without lifestyle changes. Some key points to consider for weight loss include:
- Achieving a 500–750 kcal/day energy deficit, which in most cases is approximately 1,200–1,500 kcal/day for women and 1,500–1,800 kcal/day for men, adjusted for the individual’s baseline body weight 1
- Using meal replacement plans prescribed by trained practitioners, with close monitoring, can be beneficial 1
- Nutrition interventions may differ by macronutrient goals and food choices as long as they create the necessary energy deficit to promote weight loss 1
It's essential to note that while some commercial and proprietary weight loss programs have shown promising weight loss results, most lack evidence of effectiveness, many do not satisfy guideline recommendations, and some promote unscientific and possibly dangerous practices 1. Therefore, it's crucial to approach weight loss under the guidance of a healthcare professional, focusing on evidence-based methods that prioritize morbidity, mortality, and quality of life outcomes.
From the FDA Drug Label
Use for weight loss in overweight adults, 18 years and older, when used along with a reduced-calorie and low-fat diet
Directions read the enclosed brochure for other important information diet and exercise are the starting points for any weight loss program. Try these first before adding orlistat.
Phentermine Hydrochloride, USP 15 mg and 30 mg is indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index greater than or equal to 30 kg/m 2, or greater than or equal to 27 kg/m 2 in the presence of other risk factors
The most effective weight loss supplement is orlistat or phentermine, as they are both indicated for weight loss in adults.
- Orlistat is used for weight loss in overweight adults, 18 years and older, when used along with a reduced-calorie and low-fat diet 2.
- Phentermine is indicated as a short-term adjunct in a regimen of weight reduction based on exercise, behavioral modification, and caloric restriction in the management of exogenous obesity 3.
From the Research
Weight Loss Supplements
The most effective weight loss supplement can vary depending on individual needs and health status. Some of the most commonly used weight loss supplements include:
- Orlistat: a lipase inhibitor that blocks the absorption of fat in the gastrointestinal tract 4, 5, 6, 7, 8
- Phentermine/topiramate: a combination medication that suppresses appetite and increases feelings of fullness 4, 7
- Liraglutide: a medication that helps regulate blood sugar levels and suppresses appetite 4, 7
- Naltrexone/bupropion: a combination medication that suppresses appetite and increases feelings of fullness 4, 7
Efficacy of Weight Loss Supplements
Studies have shown that these supplements can be effective for weight loss, particularly when combined with a hypocaloric diet and lifestyle modifications. For example:
- Orlistat has been shown to result in a weight loss of 7.9-10.2% in obese non-diabetic individuals, and 6.2% in obese patients with type 2 diabetes 5
- Phentermine/topiramate has been shown to result in a weight loss of 6.8% 4
- Liraglutide has been shown to result in a weight loss of 5.4% 4
- Naltrexone/bupropion has been shown to result in a weight loss of 4.0% 4
Safety and Tolerability
While these supplements can be effective for weight loss, they may also have side effects and interact with other medications. For example: