Does the composition of a meal play a big, or small, role in food's thermogenic effect on the body?
According to Diet Induced Thermogenesis (Nutrition &amp; Metabolism, 2004), the percent of calories converted to heat depends on a nutrient:


Proteins: 15-30%
Alcohol: 10-30%
Carbohydrates: 5-10%
Fats: 1-3%
A mixed meal: ~10% (this is an estimated average)


The thermic effect of nutrients is not a fixed value and can vary greatly within a person and from person to person:


  Reported intra-individual variability in DIT, determined with
  ventilated-hood systems, is 6 to 30% [7,8]. Reported within-subject
  variability in DIT, determined with a respiration chamber, is 43 to
  48%.