When it comes to weight loss, decreasing your caloric intake by restricting food and increasing your caloric burn through physical exercise is a tried and true method that works for many. But this process can be slow and difficult to maintain, and many people who take this route feel they could use a boost.

Certain medications may have the alluring potential to assist people in reaching their weight loss goals. Metformin (brand names: Glucophage, Fortamet, Glumetza), an antidiabetic medication often prescribed for the treatment of type 2 diabetes, has been touted in some circles as being such a drug. But is this just hype, or are there valid scientific reasons to consider metformin a potential valid addition to a weight loss plan?

What is Metformin?

Many people are familiar with the role of insulin in diabetes treatment. Fewer are aware that antidiabetics are an entire class of medications, only some of which are insulin derivatives or analogues. Many antidiabetics function in novel ways by influencing other aspects of the complex metabolic pathways that result in diabetes. Metformin is one such non-insulin antidiabetic drug.

Metformin functions by decreasing inputs of sugar into the bloodstream from the liver and increasing the release of sugar from the bloodstream into cells. By tipping the balance of inputs and outputs in this fashion, metformin can reduce blood sugar levels and decrease the likelihood or incidence of hyperglycemic episodes.

This mechanism explains why metformin is not effective for type 1 diabetics. Increasing insulin sensitivity within the body is excellent if your pancreas produces insulin that your body just doesn’t respond well to, but totally useless if your pancreas doesn’t produce insulin at all. However, this mechanism may lend some utility to other use cases, namely, for treating obesity.

Metformin for Weight Loss: What’s the Big Idea?

If metformin was specifically developed for the treatment of diabetes, why would anyone believe it might also be effective in assisting with weight loss? There are two important points to consider in answering that question.

First, the evidence is not yet clear as to whether, or to what extent, metformin does in fact help with weight loss (but more on that later). Second, even if metformin does help with weight loss, researchers and experts are not exactly sure why, though they have several theories.

One theory posits that the very same mechanism that makes metformin useful for controlling blood sugar makes it simultaneously useful at controlling fat storage. The theory goes, in simple terms, that releasing less sugar from the liver while also increasing demand from cells will cause the body to mobilize its fat stores as a means maintaining sufficient energy supply in the form of blood sugar.

Other theories suggest that the weight loss has more to do with metformin’s impact on the body’s levels of a hormone called GLP-1. This naturally occurring hormone is typically released following a meal and causes a cascade of effects that might reduce hunger levels and increase insulin sensitivity. This, in turn, makes a person less likely to consume unnecessary calories and more likely to deplete blood sugar before it can be converted to stored fat. Other medications already take advantage of GLP-1 and its weight loss potential, like Ozempic and Wegovy. It would therefore be unsurprising if this turned out to explain metformin’s apparent weight reducing effects.

What the Research Says

The promise of a miracle weight loss drug has turned heads in the scientific community, and some researchers have already begun looking into the matter. One study[1] found that, over 24 weeks, participants given metformin lost up to 18 lbs of weight which the researchers speculated was due to a decrease in caloric intake. A more recent and much larger study[2] sought to test the robustness of these results by repeating a similar analysis on a much larger participant sample. That study also found success, though it showed a much more modest weight reduction at only 5.3 lbs over four years.

Currently, the evidence for metformin’s efficacy seems to be too inconsistent for the FDA to approve. It has also not yet undergone the necessary clinical trials to show its safety and efficacy for the specific indication of weight loss. However, because metformin has been used and tolerated well by type 2 diabetic patients for decades, many physicians consider metformin safe to give their patients as a means of assisting them with their weight loss goals. Your doctor should always have the final say on what medications you take, so always consult with them before making any changes to your medication regimen.

Who Should Consider Using Metformin?

Metformin, or any weight loss medications, should only be considered in light of discussions between you and your physician. However, certain segments of the population may stand to benefit more from adding metformin to their regimen than others.

Perhaps the most important distinction to make here is between those who are currently trying to manage their weight with a variety of healthy lifestyle changes and are not seeing the desired results, versus those who see metformin as an alternative to diet and exercise. Metformin can supplement a healthy lifestyle but is not intended to replace one. We should also say that weight loss can be a part of a journey towards a healthier life, particularly for diabetics, but losing weight is not inherently good or desirable. Consider reflecting on the reasons for your weight loss goals, and if turning to pharmaceuticals is really something you feel is important to you.

For those who seek to add support to their diet and exercise regimens, research has suggested that metformin may be effective for diabetics and non-diabetics alike. However, type 2 diabetics or people with severe insulin resistance have been shown to experience significantly greater results from metformin than their insulin sensitive counterparts[3]. So, if you have diabetes and would like to lose weigh more quickly, than metformin could simultaneously help treat your diabetes and obesity. For non-diabetics, you may still see some effect from metformin, but likely not as much as diabetics could.

Potential Side Effects

Metformin has been used for decades and is generally regarded as a well-tolerated and relatively safe medication. However, no medication is truly “safe”, as they all have the potential to interfere with normal bodily function in a way that leads to side effects. Metformin is no exception and can cause a range of mild to severe complications.

At the mild end of the spectrum are gastrointestinal disturbances. Vomiting, nausea, abdominal pain, and diarrhea can all result from metformin usage but can often be managed by altering the dosage or avoiding taking the medication on an empty stomach. More serious complications can include lactic acidosis, a severe and acute condition caused by excessive lactic acid in the bloodstream. Thankfully, this is rare, and primarily affects those with pre-existing conditions such as kidney or heart disease. Still, all metformin users should watch for symptoms, which may include breathing difficulty and widespread muscle weakness.

To minimize the risk of side effects, be fully transparent with your doctor about your medical history, including your family’s history of illnesses, any medications you’re taking, and any illnesses you’ve suffered in the past. Always take medications exactly as directed, and immediately report any unusual symptoms to a healthcare professional.

Alternatives

As America has increasingly struggled with its weight over decades past, many drugs have been created that have promised some degree of assistance with weight loss. Metformin is an excellent example, but many other antidiabetics or medications in other classes altogether exist with similar purported effects. Consider exploring these metformin alternatives with your doctor.

Liraglutide

Earlier we mentioned that metformin might not be the only medication to function via the GLP-1 system. Liraglutide (sold under brand names Victoza & Saxenda) also takes advantage of the effects of GLP-1, though in a different way. Rather than increasing the expression of GLP-1, this medication mimics its presence, causing its receptors to be activated in the same manner. The resulting effects are similar to metformin: greater regulation of appetite and blood sugar, and consequently improved weight reduction.

This medication is only available by prescription and has a well-tolerated safety profile. Side effects can include abdominal disturbances such as diarrhea and nausea. Due to the chemical properties of Liraglutide, this medication cannot be taken orally and must be injected subcutaneously.

Orlistat

Orlistat (sold under brand name Xenical) is a unique medication compared to the others listed here. Its mechanism of action does not target cravings or blood sugar, but rather tackles fat gain at the source. By blocking the intestines’ ability to process dietary fats, the body is less able to absorb and store said fat. This mechanism has been demonstrated to contribute to weight loss when taken in conjunction with effective diet and exercise.

Though potentially effective, interfering with fat digestion can cause some nasty side effects. Fecal incontinence and an increased urge to defecate are two complications that can make orlistat an unfavorable choice for some.

Phentermine

This medication is technically classified as a stimulant, and aids weight loss by causing certain chemicals, called catecholamines, to be released. These chemicals reduce cravings and appetite, causing users to eat less. Phentermine usage has been shown to result in weight loss when used as part of a regimen.

While Phentermine can be an effective tool, it is a controlled substance and is not intended to be used for long periods of time. Side effects can include high blood pressure, heart palpitations, dry mouth, and insomnia.

Conclusion

Losing weight and treating diabetes can both be worthwhile goals. Both can be treated in a variety of ways, many of which revolve around controlling aspects of a healthy lifestyle, like staying physically active and controlling your food intake. Refining your habits in these areas can go a long way towards achieving your desired outcomes in a healthy way, while bringing many positive improvements to other aspects of your overall well-being.

However, medications can, and in some cases should, play an important role in your overall approach to treating diabetes or obesity. They won’t be appropriate for everyone, but under the guidance of a doctor, you may find that certain medications can help give you the nudge you need to take control of your weight. Metformin is a mature and well-known medication that may be an excellent place to start. Consider speaking to your doctor about metformin, and always follow your doctor’s directions regarding medication usage.

[1] https://pubmed.ncbi.nlm.nih.gov/9526970/

[2] https://pubmed.ncbi.nlm.nih.gov/17145742/

[3] https://pubmed.ncbi.nlm.nih.gov/23147210/