Can Metformin help you lose weight?

Metformin is known to be marginally beneficial for weight loss[8][9]. How does it do that? Metformin stimulates the breakdown of fat. It also lowers your blood glucose, which leads to less insulin needing to be released.

Since insulin is a fat-storing hormone, lower insulin levels make your stored body fat more accessible. You have plenty of energy stored as fat, so by making these stores accessible your metabolism can rely on more fat for energy; this helps normalize appetite and lose excess body fat.

An overproduction of insulin can eventually lead to insulin resistance. This is the phenomenon whereby cells become less and less responsive to insulin so more and more of it is needed to perform its action. Hence, this insulin-lowering effect of Metformin is especially beneficial for people who are insulin resistant.

Diabetics aren’t the only ones who are insulin resistant. Many people also have prediabetes (often without knowing it) or some kind of underlying insulin resistance. Having said that, although metformin facilitates weight loss for a while it is not an effective weight-loss tool. It is more efficient over 3 months when used in combination with other drugs, such as GLP-1 agonists[10].

These benefits are likely easily lost by spiking your blood sugar with refined carbs. Metformin is much more efficient when combined with a low carb or ketogenic diet and may become unnecessary in many cases[11].

Metformin as an anti-aging drug

Scientists are still looking for the secret of healthy aging and metformin might take them a bit closer. One study observed that diabetes patients taking metformin lived longer than the control group without diabetes[12]. Considering that diabetes is a risk factor for a variety of life-threatening diseases, this is an astonishing result.

However, as interesting as this correlation is we do not know if metformin improves longevity or if so, how. Metformin decreases insulin levels, IGF-signaling, inflammation, and oxidative stress.

It is also thought to activate AMPK and thereby inhibits mTOR. mTOR inhibition is known to be involved in mechanisms linked to increases in lifespan. AMPK and mTOR act as energy sensors and low nutrient-availability is well-known to improve longevity[13]. Metformin seems to mimic calorie-restriction, which probably contributes to its life-extending effect.

Before you jump into taking metformin: it is even less clear if the life extension correlation in diabetics is even relevant to non-diabetics. Your efforts are still best focused on smart lifestyle changes – sorry!

Metformin for the treatment of PCOS

Polycystic ovary syndrome (PCOS) is a hormonal disorder that occurs in women and is associated with high levels of androgens (male hormones) and insulin resistance. Common symptoms of PCOS are fertility problems, weight gain, skin problems, and an increased risk of type 2 diabetes.

Insulin resistance is thought to play a causative role in PCOS[14]. Insulin, together with IGF, stimulates the ovaries to release higher levels of testosterone. This leads to problems in the release of eggs during ovulation and often even pregnancy.

Metformin is used to treat infertility in women with PCOS and can also relieve other symptoms. Metformin’s beneficial effects are thought to be due to its insulin-sensitizing abilities. Clomiphene, an ovulation-inducing agent, is used as first-line therapy for infertility treatment in PCOS.

In non-obese women, metformin treatment results in pregnancy rates that are comparable to treatment with Clomiphene. This is, however, not the case in obese women, in which Clomiphene is more efficient[15].

But obesity is a risk on its own right and weight loss is recommended in any case when planning to get pregnant. Since metformin is only a weak insulin-sensitizing agent, it is feasible that the additional obesity-associated insulin resistance is too much for Metformin to be beneficial.

Besides increasing the chances of pregnancy, weight loss is known to improve PCOS symptoms considerably. Because the ketogenic does not only facilitate weight loss but also lowers insulin, it is not surprising that it can benefit women with PCOS. In one study, women dropped weight by an average of 12% and reduced fasting insulin levels by 54%[16].

Metformin and exercise

Metformin and exercise are both known to increase the insulin sensitivity of muscle cells. So you would expect that both in combination potentiate this effect, correct? On the contrary actually! One study showed that Metformin can reverse the insulin-sensitizing effect on muscle cells usually seen after aerobic exercise. They suggest this occurs due to decreased mitochondrial respiration; less oxygen can be used by these organelles to supply energy to the cell (ATP).