Acute Effects of Coffee on Appetite and Inflammation Markers, Glucose Metabolism and Energy Intake

Acute Effects of Caffeinated and Decaffeinated Coffee Consumption on Energy Intake, Appetite, Inflammation and Glucose Metabolism

The purpose of the study is to investigate whether caffeinated and decaffeinated coffee consumption has acute effects on subjective appetite feelings, energy intake and biochemical markers related to appetite, inflammation and glucose metabolism compared to water consumption.

Coffee is a pharmacologically active, widely consumed beverage. Scientific interest in relation to coffee consumption has been revisited the last decade in the light of new, mainly epidemiological, evidence indicating its potential health benefits. In specific, both cross-sectional and prospective studies indicate that coffee consumption is associated with a lower risk for type 2 diabetes. Furthermore, an inverse association has been found between coffee consumption and markers of inflammation and endothelial dysfunction in healthy and/or diabetic participants, although the opposite effect has also been reported, mainly in relation to inflammation markers. In relation to body weight, epidemiological data suggest that increment in caffeine consumption is associated with lower mean weight gain and energy intake during a 12-y period.

However, information from clinical studies is scarce. Acute caffeine and/or coffee consumption have been associated with impaired glucose metabolism and insulin resistance. In relation to inflammation, animal studies have indicated a beneficial or no effect of coffee consumption, whereas a clinical study in humans found an increase in adiponectin and a decrease in interleukin-18 (IL-18) blood concentrations after a monthly intervention including daily consumption of 8 cups of coffee. As far as energy balance is concerned, there is an early experiment demonstrating that the ingestion of 300 mg of caffeine prior to food intake, compared to the non-caffeine intake, significantly reduced energy intake by 21.7% in men, but not in women. A more recent study has found that the combination of caffeine and red pepper is positively associated with energy expenditure and negatively with energy intake, whereas, it has also been reported a positive association between habitual caffeine intake and body weight loss achieved through a very-low-calorie diet.

Taking into consideration the limited clinical evidence regarding the acute effect of coffee consumption on appetite-related markers, subsequent energy intake and inflammatory markers, we undertook a clinical study of crossover design to investigate the short-term changes on energy intake, subjective appetite ratings, appetite hormones, inflammation markers and glucose metabolism after caffeinated and decaffeinated coffee consumption.

Inclusion Criteria:

• healthy
• non-obese

Exclusion Criteria:

• smokers
• restrained eaters (as this was evaluated using the Dutch Eating Behaviour Questionnaire and a total score > 2.5)
• those who reported slimming or any other dietary regime
• abstainers from caffeine sources
• athletes during competition period
• participants with a known diagnosis of either hypertension, diabetes, impaired glucose tolerance or a fasting blood glucose concentration above 125 mg/dl
• subjects on medication for hypertension or on medication known to alter glucose metabolism
• subjects who were on medication that may have an impact on appetite and sensory functioning or who reported a metabolic or endocrine disease, gastrointestinal disorders, or a history of medical or surgical events that may have affected the study outcomes