Coffee is known for its positive effects on long-term health. Drink the equivalent of three to four cups of instant coffee per day reduces the risk many health problems, including heart disease, type 2 diabetes, and certain cancers.
Most people win small amounts of weight each year as they age. But can coffee help prevent this gradual weight gain?
A group of researchers examined whether drinking an extra cup of coffee per day – or adding sugar, creamer or a non-dairy alternative – led to more or less weight gain than those who didn’t. did not adjust their consumption.
Their research (currently a pre-proof, meaning it has been peer-reviewed but has not yet undergone final formatting and editing) found a modest link between coffee and less than expected weight gain .
People who drank an extra cup of coffee per day gained 0.12 kg less weight than expected over four years. Adding sugar resulted in slightly more weight gain (0.09 kg) than expected over four years.
How was the study conducted? What did he find?
The researchers combined data from three large studies conducted in the United States: two Nursing Health Studies from 1986 to 2010, and from 1991 to 2015, and a Health Professional Follow-up Study from 1991 to 2014.
The Nurses’ Health Studies are two of the largest cohort studies, with more than 230,000 participants, and study chronic disease risks in women. The Health Professional Tracking Study involves more than 50,000 male health professionals and investigates the relationship between diet and health outcomes.
Participants in all three studies completed a baseline questionnaire and another questionnaire every four years to assess their food and drink consumption. Using the combined data sets, the researchers analyzed changes in coffee consumption and changes in participants’ self-reported weight at four-year intervals.
The average four-year weight gains for the nursing studies were 1.2kg and 1.7kg, while participants in the healthcare worker study gained an average of 0.8kg.
The researchers found that an increase in unsweetened, caffeinated, or decaffeinated coffee consumption of one cup per day was associated with 0.12 kg less weight gain than expected over four years.
Adding cream (milk) or a non-dairy alternative did not significantly affect this weight change.
However, adding sugar (one teaspoon) to coffee was associated with 0.09 kg more weight gain than expected over four years.
These associations were stronger in participants who were younger and had a higher body mass index at the start of the studies.
What are the advantages and disadvantages of the study?
This study is unique in two respects. The sample was very large and followed participants for many years. This adds confidence that the associations were real and can likely be applied to other populations.
There are, however, three reasons to be careful.
First, the results represent a associationnot causality. This means that the study does not prove that coffee consumption is the real reason for the weight change. Rather, it shows that the two changes were observed together over time.
Second, the results regarding weight were very modest. The average weight gain avoided over four years, based on one cup of coffee, was 0.12 kilograms, or about 30 grams per year. This amount may not be a significant change for most people looking to manage their weight.
Finally, this analysis did not take into account the variability in the amount of caffeine in coffee (which we I know it can be high), he simply assumed a standard amount of caffeine per cup.
How Could Coffee Help With Weight Management?
Caffeine is a natural stimulant that has been shown to temporarily reduce appetite and increase alertness. This may help you feel less hungry for a short time, which could lead to a reduction in energy intake.
Some people consume coffee before exercise as a stimulant for improve their training performance — if a workout is more effective, more energy can be expended. However, it is generally believed that the benefits will be short-lived rather than long-term.
Caffeine has also been shown to speeds up our metabolism, resulting in burning more energy at rest. However, this effect is relatively small and is not a suitable substitute for regular physical activity and a healthy diet.
Finally, the cafe has a slight diuretic effect, which can cause temporary loss of water weight. This is water loss, not fat loss, and the weight is quickly regained when you rehydrate.
Is it worth trying coffee for weight loss?
Weight loss can be influenced by a variety of factors, so don’t get too excited about the coffee-weight connection highlighted in this new study, nor increase your coffee consumption to unreasonable levels.
Most adults can consume safely 400 mg of caffeine per day. That’s the equivalent of two espressos or four cups of instant coffee or eight cups of tea.
If you are pregnant or breastfeeding, it is important to talk to your doctor before increasing your caffeine intake, as caffeine can pass to your growing baby.
If you need personalized weight advice, talk to your GP or visit a registered practicing dietitian.
Lauren Ball is Professor of Community Health and Wellbeing at the University of Queensland and Emily Burch is a dietitian, researcher and lecturer at Southern Cross University. This piece first appeared on The conversation.