What Is AMPk? A Key Metabolic Regulator Explained

AMPk is a molecule and is more technically known as AMP-activated protein kinase. In recent studies, this molecule has become something of a star player when looking at the processes behind weight loss, energy and muscle building. This makes it a substance of interest for anyone trying to lose weight or improve their performance…

Much of what we known about AMPk is theoretical at this stage and not highly actionable. Nevertheless, there do appear to be ways we can increase its role in our bodies, so let’s take a look at what those methods involve and just how we can leverage what we know to potentially profound effects.

Stimulating AMPk

AMPk is a ‘heterotrimeric compound’ meaning it contains three separate parts. Essentially this substance is ‘turned on’ whenever the cellular energy state of a cell drops. When our bodies have converted all available ATP into ADP, AMPk is signaled. In the muscles meanwhile, depletion of glycogen appears to trigger its release (glycogen being an immediate source of glucose stored in the muscle cells). Glucose deprivation, oxidative stress, hypoxia (lack of oxygen), ischemia (decrease in blood flow) and more, all seem to activate AMPk.

In short though, the main way to activate AMPk is through exercise. And at the point where we start to run low on energy it signals. At this point AMPk is also triggered in the fat cells and liver. Hormones such as leptin and adiponectin also activate AMPk and are often released by the fat cells in response to nutrient surplus.

What Does AMPk Do?

The role of AMPk appears to be to signal the body to start getting more energy from various sources. It does this by inhibiting glycogen storage and increasing glucose uptake. This way it can improve insulin sensitivity and it’s believed that many insulin sensitizing drugs such as metformin and TZDs work partially through the activation of AMPk.

In the liver, AMPk decreases fatty acid and cholesterol synthesis, leaving more energy in the blood for exercise/other functions and preventing the storage of fat. In the muscles, AMPk can increase fat oxidization – helping us to burn more fat in order to power through a set of exercises. It does this at least partly by increasing production of CPT1 – carnitine palmitoyltransferase).

Unfortunately though, AMPk does also have a couple of other unwanted side effects. As well as preventing fatty acid synthesis, AMPk also appears to reduce protein synthesis which could have negative impacts on muscle growth. Further, it also appears as though AMPk can increase appetite and is correlated with increased levels of ghrelin.

AMPK is more active in slow-twitch muscle fiber compared with fast-twitch types, showing its usefulness for ‘endurance’ type activities (1).

Using This Information

AMPk is thus a little contradictory in terms of its usefulness, though it does explain a lot of what we know already. Increase AMPk activation and you increase energy levels while also burning more fat: unfortunately, it will also increase your appetite and may prevent muscle gain. You could make this happen through not eating, and it explains one of the reasons that bodybuilders often lose a lot of muscle when ‘cutting’.

On the other hand, decrease AMPk – potentially by eating large amounts – and your appetite will be suppressed and you’ll build muscle, but you’ll possibly find it hard to keep off the unwanted fat storage.

So what good is this information to you? Well, for someone ‘bulking’, decreasing AMPk would be useful – but it pays to be aware that fat gain will also be accelerated. For someone dieting or trying to increase their energy levels, increasing AMPk could be helpful – but it’s again useful to just be aware that an increase in appetite is likely, as is a loss of muscle. Using BCAAs (branch chained amino acids) may help to prevent muscle loss while trying to increase AMPk.

How to Increase AMPk

The main way to increase AMPk is by increasing exercise (resistance, aerobic and especially anaerobic) or by reducing food intake – possibly even using intermittent fasting, or fasted cardio (2).

Other than diet, it appears that supplementation may also be able to help increase AMPK. In one study (link unavailable), it was found that giving lab rats a lutein supplement with full-fat milk (to aid digestion) could increase the amount of time they spent running on a treadmill of their own accord – running as much as 30km a week more than control groups. This suggests that the mice had more energy and it led to an increase in weight loss. Researches were then able to identify an increase in both CPT1 and AMPk in the cells of the mice.

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