Effects of Caffeine and Coffee on Resting Metabolic Rate, Comparing Normal Weight Men to Obese Men
Condition: Asymptomatic Conditions
MeSH terms: Asymptomatic Diseases
Study type: Interventional
Phase: Phase 3

Summary: 
      Background. The prevalence of obesity has increased in the last two decades. To maintain body
      weight energy expenditure (EE) should be equal to energy intake (EI). A low EE predisposes
      individuals to weight gain and to obesity that can also results from low resting metabolic
      rate (RMR). Caffeine (Caf) is an active food ingredient and is widely consumed globally, and
      has an important impact on energy balance. Caf reduces appetite (EI) and increases EE, thus,
      Caf has a potential role in body weight reduction. Caf causes higher total daily energy
      expenditure (TDEE) in normal weight (NW) people compared to obese (OW). Moreover Caf is
      linked to decreased fat oxidation in OW. There are differences between OW and NW in Caf
      pharmacokinetics, but no differences reported between NW and OW females in its effects on
      RMR. There is a gender difference in the influence of Caf on metabolism. The investigators
      are aware of no previous studies which compared the effect of Caf on the RMR of NW and OW
      men.

      Objectives. 1) To compare the effect of Caf and coffee on resting metabolic rate (RMR) values
      in healthy normal-weight (NW) men and overweight (OW) men. 2) To develop Caf intake frequency
      questionnaire (in Hebrew)

      Hypothesis. RMR values will be higher and respiratory exchange ratio (RER) values will be
      lower in NW compared to the values measured in OW men.

      Methods. 33 men (16 NW and 17 OW) were reported to the laboratory on 4 separate occasions
      (placebo, Caf tablets, coffee and decaffeinated coffee). During the lab sessions they were
      undergo complete anthropometric measurements and RMR measured (one of the study conditions)
      using indirect calorimetry. Additionally, respiratory exchange ratio (RER) which is
      calculated as the ratio between CO2 production (VCO2) and O2 consumption (VO2) (VCO2/VO2),
      blood pressure and heart rate (HR) response recorded.

      The importance of this study is that the results will contribute to the scientific basis of
      weight control and health interventions programs (diet and physical activity) in overweight
      men.
    

Detailed description: 
      Methods. 16 NW and 17 OW men were reported to the laboratory on 4 separate occasions
      (placebo, Caf tablets, coffee and decaffeinated coffee) each separated by 2-7 days. Before
      the first meeting they refill caffeine, physical activity and medical questionnaires. The
      investigators recruited only men who were healthy non-smokers with no comorbidities and the
      daily caffeine consumption was under 400 mg. Before each meeting participants had to comply
      guidelines outlined included fasting for 8 hours, avoiding intense physical activity 14 hours
      and moderate exercise 2 hours before measurements. The meetings conducted in the morning when
      the first session included anthropometric measurements (weight, height and waist
      circumference) and body composition measurements using Bioelectrical Impedance Analysis (BIA)
      and a digital caliper. Each session began with a measuring resting blood pressure and heart
      rate (Polar telemetric systems), after that participants were given randomly placebo or Caf
      tablets or coffee or decaffeinated coffee, waiting half an hour and then measuring the RMR
      and respiratory exchange ratio (RER), for half an hour using indirect calorimetry (canopy
      system). Then again measured blood pressure and heart rate at rest.

      The sample size was calculated for 16 participant in each group, according to an expected
      change of 3% at RMR values between the groups with the power of 80% and significance of 0.05
      . standard deviation (SD).
    

Intervention name(s): Caffeine; Placebo; Coffee; Decaffeinated
Intervention type(s): Dietary Supplement; Dietary Supplement; Other; Other
Intervention description(s): 200 mg of caffeine capsule before RMR measurement; Placebo capsule (starch) before RMR measurement; 9 grams of black coffee in boiling water consumed before RMR measurement; 9 grams of decaffeinated black coffee in boiling water consumed before RMR measurement
Intervention MeSH terms: Caffeine
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science