Coffee. It’s like the world’s favourite elixir. Mine included. For an athlete, there are many studies supporting its use as an ergogenic aid for athletes – helping reduce rates of perceived pain and effort, improving muscle fibre recruitment and enhancing glycogen repletion post-workout. These benefits are individual, however, and while research suggests that genetic differences in our ability to detoxify caffeine could account for this, it is not a universal finding. This is something true for athletes and non-athletes alike.
Other features of coffee are also salient for all individuals. Caffeine is ketogenic; not only can it help mobilise fatty acids to be used for energy, it increases the presence of ketones in the bloodstream – hence it is a good pre-workout fuel to help elicit fatty acid oxidation pathways and provide fuel for the workout in the absence of glucose. This doesn’t necessarily translate in additional body fat loss (more important lifestyle strategies are required for that, such as a caloric deficit, resistance training, reduction in stress etc), but can encourage these energy pathways to be upregulated, helping in the process of becoming adapted to a lower carb dietary approach.
Coffee improves insulin sensitivity and glucose tolerance (potentially related to the polyphenols present, though the mechanism is currently unclear), therefore enhancing the effects of both a lower carb approach, or a plan that includes fasting (either intermittent fasting, super-fasting, or a 5:2 approach such as the one in my fat-loss plans). Further, anyone doing my accelerated fat loss plans who have that 16h intermittent fast on the ‘fasting mimicking’ days could experience a more potent effect from the fast by including black coffee alongside water as their beverages of choice.
Autophagy, where our body starts to clear out damaged cells from the liver, heart and muscle tissue, is one of the benefits of fasting as you know. In mice models it might take just 16 hours for this to occur, in humans it is likely to take a lot longer given the differences in our metabolic rate (a mouse has a faster metabolism). Consuming caffeine on an empty stomach (or as part of a fast) promotes autophagy, which theoretically would shorten the time that is required to fast to stimulate this process. It also triggers AMPK, an enzyme that inhibits fat storage, promotes fat burning and activates antioxidant networks. These properties are thought to underpin much of the purported health benefits of drinking coffee.
It IS a balance though – if you’re following a fasting protocol, working out, and reading this at 3.30am in the morning, it’s a good sign that your brain is wired – raising cortisol to the extent that it’s (quite obviously) disrupting sleep. When we fast, like exercise, it places a stress on the body – this is where many benefits come from, as your body responds and adapts, becoming more resilient. However, too much of anything is too much! If coffee on top of your fasting regime or exercise program (or, life in general) is causing this stress response, then it is worth dialling it back a bit (or go 1/2 and 1/2 with decaf) to see if this changes your stress response.
Caffeine (or coffee), though, may not be good for anyone with gut issues. As it can stimulate the stomach cells to release more gastric juices, aiding in digestion, we often hear that too much coffee promotes a highly acidic environment and as such, could increase the risk of damage to the cells and subsequent gut issues. The literature, though, reports that caffeine does not negatively impact gastric or duodenal ulcers, and in fact when administered in vitro, could help repair cells damaged by inflammatory bowel conditions such as ulcerative colitis, and is also protective for the mucosal layer of the gut. Research suggests this is because caffeine increases blood flow to the gastrointestinal tract. Conversely, caffeine can lower the tone of the oesophageal sphincter – the valve that controls the release of stomach acid into the oesophagus, thus may promote heartburn and reflux.
With all research studies, it’s important to remember you are your own best investigator when it comes to how coffee affects you. I’ve said this before, but a good point to reiterate. The best advice, then, is to pay attention to how you feel when you drink coffee. Does drinking coffee make you more wired, especially when you fast, indicating it stimulates your stress (or cortisol) response? Does it give you reflux or heartburn? Does it upset your digestive tract more than settle it? Everyone has a different tolerance level to coffee, and further, our ability to detoxify it may also be different. If you feel great when you have coffee, and you don’t have any gut-related issues, then it is likely absolutely fine for you. If you notice an irritated gut, or you feel a bit wired, then it isn’t worth persevering with coffee for the purported health benefits – in your case, it might be making things worse.