Throwing aside all of the variables, as Uncle Bob noted, here is what I found regarding the use of cayenne pepper to increase calorie burning metabolism:
1 gram (about 1/2 teaspoon) of cayenne pepper will boost your calorie burning metabolism enough to burn off about 15 calories per day. The studies done in England used 3g - and the actual results ranged from 4-76 calories per day ... the 45 cal/day was the average they they came up with ... which translates into 15 cal per gram.
But, it's not all that simple ... increased capsaicin intake can slow fat metabolism in the liver which can alter cholesterol production and LDL/HDL triglyceride levels, and thus could mean your body absorbes less fats than normal ... but, it also depends on other factors like protein intake, and the protein sources.
You have a couple of alternatives to achieve the same goal:
1) eat fewer calories per day
2) take a walk around the block after dinner/supper
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain