August 13, 2018

Coffee: how much is too much?

By dryeongs

Photo by Tyler Nix on Unsplash

Coffee. The national beverage of Australia (arguably competing for that title with beer), we pride ourselves on having a coffee palate like no other country (I’m looking at you, Starbucks-swigging United States). But how many is too many? Are there any health benefits to our daily pick-me-up?

The information in this post primarily comes from the Australian and New Zealand Food Standards’ (ANZFA) Publication on the Safety Aspects of Dietary Caffeine, as well as this site and this site from

A distinction has to be made between the health effects of coffee, the beverage and caffeine, the chemical. Studies have been done on both individually and there seem to be some unique health benefits of coffee specifically, beyond the effects of caffeine.

NOTE: Caffeine is also found in many soft drinks, energy drinks, and sport supplements.

What are the health benefits of coffee?
Specifically, caffeine has been found in various studies to have the following benefits:
– increases alertness and reduces fatigue
– improves performance on certain cognitive tasks
– potentially improves cognitive performance with long term exposure
– improves anaerobic running capacity (sprinting)
– increased power output with resistance training
– increased aerobic exercise capacity
– increased metabolic rate

As a beverage, other studies have found that coffee seems to:
– increase HDL (“good”) cholesterol
– reduce inflammatory markers

Of course, these studies vary in size and design, so the results are difficult to apply in the real world. I guess probably the most interesting benefit of caffeine might be the increased metabolic rate, which could potentially lead to weight loss. This explains why caffeine is usually one of the top ingredients in weight loss supplements. However, the studies have to be approached with caution as it appears there is no weight loss benefit with long term use. The likely explanation is that tolerance develops over time. So, if used to assist with weight loss, it should be consumed intermittently, and always in conjunction with an appropriate diet and exercise program.

Caffeine does seem to hold up to scrutiny with regards to sporting performance, which is demonstrated by the large number of pre-workout supplements containing caffeine. In my own personal experience as a runner, I have found that the mental and physical rigors of long distance running are better tolerated with a pre-run caffeine shot, as has my cycling counterpart.

What are the possible side effects of coffee?
As with anything, consuming too much caffeine can lead to some untoward side effects. At what dose these side effects are experienced can vary from individual to individual.

According to the ANZFA, doses of >500mg a day can result in increased anxiety and sleep impairment. High doses can also potentially cause elevations in blood pressure, increased levels of cortisol (a stress hormone), and an increased heart rate, which is why patients with irregular heart rhythms are advised to limit their caffeine intake. Coffee may also exacerbate acid reflux or cause gastrointestinal distress in some susceptible patients.

But how much is too much?
This is a difficult question to answer. It is very subjective, and most patients simply need to be aware of their own response to caffeine. An average cup of instant coffee has approximately 57mg of caffeine, while a shot of espresso contains about 77mg- see here for an infographic of caffeine content in popular beverages. So with an upper limit of 500mg (the European Food Safety Agency and the US National Academies of science suggest 400mg), that leaves room for…quite a few cups of coffee, probably more than what most of us consume in a day. However having said that, caffeine sensitivity varies greatly from individual to individual. Everyone has that friend who takes one sip of coffee and feels immediately energetic, and that other friend who can drink 3 cups before bed and feel nothing. So, to summarize, listen to your body and know your limits. Remember tolerance develops over time, and some people lose the energy-sustaining capacity of caffeine the longer they drink it. When that happens to me, I just switch to tea or decaf for a few weeks before starting up again.

How does it fit in with my weight loss and healthy lifestyle goals?
It can fit in quite easily, depending on what coffee you drink. If you’re having cream, 3 sugars and chocolate sprinkled on the top, then no, it’s not going to be the best drink for someone trying to lose weight. Most people don’t even factor their daily coffee as part of their energy intake for the day, and black coffee on its own has very little calories. It’s the milk and sugars that can cause extra calories to sneak into your day. So, if you’re watching your weight, you don’t need to skip the coffee! Just avoid adding sugar and switching out your full fat milk for skim milk, or drink it black.

So, to conclude, that daily cup of coffee is most likely not doing you any harm, and could potentially be doing you some good. Just watch the sugars.