Always on the lookout for ways to boost weight loss, many Canadians are keen to learn more about whether coffee speeds up metabolism and weight loss. Indeed, several studies have concluded that metabolic rate or energy expenditure is positively affected by coffee consumption. For example, a study in the American Journal of Physiology (reference link) in 1995 showed that energy expenditure increases by about ten per cent in response to caffeine ingestion. Less clear is whether that increase is then translated into actual weight loss and whether the increase is sustained over time.

Coffee could be the ideal pre-exercise beverage. Research indicates coffee has a positive role in endurance exercises such as running and swimming, helping people work longer and harder. A widely respected study published in 1978 in the Journal of Medical Science and Sports (reference link), showed that following coffee consumption subjects were able to perform longer and reported that exercise felt easier than without coffee. More recently, a research review in the International Journal of Sports Nutrition, Exercise and Metabolism (reference link) summarized a full roster of published studies in this area and concluded that caffeine improved athletic performance by 12 per cent.

For athletes, adequate hydration is key and it is often assumed that coffee consumption can lead to dehydration and therefore limit performance. However, research does not bear this theory out. In a comprehensive research review on this subject published in the International Journal of Sport Nutrition and Exercise Metabolism (reference link) in 2002, authors concluded that athletes or those exercising recreationally are not at risk of fluid imbalances as a result of moderate coffee consumption. In fact, coffee can be consumed as part of daily recommended fluid intakes.

It is widely accepted that coffee affects brain function in various ways, including mental performance, alertness and impact on sleep patterns.
In an extensive research review published as the Handbook of Human Performance (reference link) on this subject, authors conclude the following:

“When caffeine is consumed in the range of doses found in many foods, it improves the ability of individuals to perform tasks requiring sustained attention, including automobile driving. In addition, when administered in the same dose range, caffeine increases self-reported alertness and decreases sleepiness.” The same review noted that the research indicates that negative effects on mental capacity can occur with excessive consumption or by those who are particularly sensitive.

Interestingly, a 2002 study published in the American Journal of Epidemiology (reference link) looked at elderly subjects and measured cognitive function against whether subjects were lifetime coffee drinkers. It found that women with higher lifetime coffee consumption showed higher mental performance on tests.

The effect of coffee on increasing alertness is well documented, with demonstrated effects on boosting alertness where it is low as well as where alertness is already at normal levels. In a related area, research supports the notion that coffee both makes it difficult to get to sleep and difficult to stay asleep, but there appears to be vast differences between individuals on the extent of this effect. Interestingly, a study published in the journal Sleep (reference link) concluded that family situations and age have more effect on sleep patterns than coffee consumption.