Studies related to and

Metabolic Effects Of Caffeine Ingestion And Physical Work In 75-year Old Citizens. A Randomized, Double-blind, Placebo-controlled, Cross-over Study

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 30
Gender Both Genders
Age Range 65+
Body Types Untrained
Notes for this study:
Persons over 70 were recruited to consume 6mg/kg bodyweight caffeine prior to an hour long cycling endurance exercise.

Insulin resistance increased (ie. sensitivity decreased) due to a conversion of metabolic substrate towards fatty acids; increases in free fatty acids, adrenaline and noradrenaline, and lactate were significantly more than placebo.

Caffeine: A Double-blind, Placebo-controlled Study Of Its Thermogenic, Metabolic, And Cardiovascular Effects In Healthy Volunteers

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 6
Gender Both Genders
Age Range 18-29, 30-44
Body Types Untrained, Overweight, Average
Notes for this study:
In low habitual coffee drinkers (150-300mL daily), supplementation of 100-400mg caffeine increased the metabolic rate (9.2+?-5.7, 7.2+/-6.0, and 32.4+/-8.2kcal/h increase) with the highest dose also increasing plasma glycerol (indicative of fat burning) and lactate. Blood pressure was increased at 400mg only in supine position.

Caffeine Can Decrease Insulin Sensitivity In Humans

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 12
Gender Both Genders
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
In 12 healthy persons, ingestion of caffeine resulted in an acute 15% decrease in insulin sensitivity. This appeared to be mediated through increased adrenaline levels (which increased 5-fold), as an adenosine antagonist dipyridamole did not induce similar effects.