AMPK and Aging

AMPK shows up in longevity marketing as a “metabolic master switch” that supplements and drugs can flip. The biology behind it is real. Humanic Blue compares that laboratory mechanism with outcomes measured in people. The evidence that activating AMPK slows human aging is, so far, essentially absent, and one popular way of doing it may work against exercise.

The reviews below describe AMPK (AMP-activated protein kinase) as a low-energy sensor involved in responses to exercise and fasting. AMPK and aging are linked in laboratory research, but that does not establish a human longevity treatment. In the National Institute on Aging’s mouse testing program, metformin alone did not significantly extend lifespan at the dose tested. Two short trials in older adults without diabetes found smaller exercise gains with metformin than with placebo. Those findings raise questions about using a diabetes drug for aging; they are not a reason to stop a prescribed treatment.

What does AMPK do?

A 2014 review in Cell Metabolism from the Harvard T.H. Chan School of Public Health examines how low-energy signals relate to aging and resistance to age-related disease. It describes AMPK as one of the sensors coordinating responses to low energy.

The authors considered AMPK a potential drug target for longevity, but cautioned that its effects are not helpful in every disease setting and that selective targeting may be necessary. Activating it everywhere is not the same proposal as targeting a particular tissue or problem.

A 2018 review in The FASEB Journal describes AMPK as sensing energy availability within cells and adjusting processes that build molecules or break them down. That puts it in tension with mTOR, the growth pathway covered in mTOR and Aging; in one of the trials below, metformin raised AMPK signaling while the increase in mTOR signaling tended to be smaller. Both relate to deregulated nutrient-sensing—changes in how cells respond to available fuel—one of the hallmarks of aging covered in Hallmarks of Aging Explained.

How people try to activate it

• Exercise. The FASEB review examines how AMPK responds to the changing energy demands of exercise and recovery.
• Fasting and calorie restriction are low-energy states of the kind AMPK senses; their evidence is covered in Does Intermittent Fasting Help You Live Longer?
• Metformin, a diabetes drug, activates AMPK, among other effects. The proposed TAME trial of metformin for aging is discussed in What Is Geroscience?
• Supplements marketed as AMPK activators. No dietary supplement has been shown in human trials to extend lifespan, as covered in Longevity Supplements: What Has Evidence in Humans?

Did metformin extend life in mice?

The National Institute on Aging’s Interventions Testing Program tests compounds in genetically diverse mice at three sites. Its 2016 report in Aging Cell found no significant lifespan extension with metformin alone at 0.1% of the diet. The metformin–rapamycin combination did extend lifespan. Comparison with earlier rapamycin-only studies led the researchers to suggest a possible additional benefit, not to establish the effect of metformin in humans.

How do differences between animal experiments affect the claim that metformin slows aging?

What happened when metformin was paired with exercise?

Strength training. In the MASTERS trial, published in Aging Cell in 2019, about 100 healthy adults aged 65 and older did 14 weeks of supervised resistance training while taking 1,700 mg a day of metformin or placebo. The placebo group gained more lean body mass and thigh muscle. The researchers reported increased AMPK signaling with metformin, with a trend toward smaller increases in mTORC1 signaling, one branch of the mTOR growth pathway. They concluded that metformin reduced the muscle-growth response to training in this population and reported no conflicts of interest.

Aerobic training. In a 2019 trial in Aging Cell, about 50 older adults (average age 62) did 12 weeks of aerobic training with metformin or placebo. The metformin group had smaller improvements in insulin sensitivity (how well the body responds to insulin) and VO2 max (the body’s capacity to use oxygen during exercise). Their muscle cells also did not show the training-related increase in mitochondrial respiration, the process that uses oxygen to make usable energy. The authors called for more research before using metformin as an aging treatment.

Long-term outcomes. The Diabetes Prevention Program randomized about 3,200 adults at high risk for type 2 diabetes to metformin, intensive lifestyle change or placebo. Over a median 21 years, metformin prevented or delayed diabetes but did not reduce all-cause, cancer or cardiovascular mortality compared with placebo (Lee et al., 2021). After the initial trial, treatments were unmasked, all groups were offered a modified lifestyle program, and out-of-study metformin use blurred the original assignments. This is evidence about a high-diabetes-risk population, not a trial of AMPK activation in healthy aging.

The exercise studies were short trials in people without diabetes. None of these studies settles the balance of benefits and risks for someone taking metformin to manage diabetes or to prevent it in an appropriately selected high-risk patient. Do not stop or change a prescribed medicine on the basis of these findings; discuss them with the prescriber.

What would show whether combining two interventions preserves each one's expected effects?