This is a difficult question to answer in terms of CO2, because it will vary widely, depending on the amount of exertion a person undergoes in a day, and what they eat.
(For methane it's easy - people *don't* exhale methane).
The estimated average daily calorie intake is 1940 calories per day for women and 2550 for men. Since you haven't specified which sex, let's take the average of 2245.
Assuming that the person is not unreasonable active (or inactive) that is the amount they'll need to consume to stay metabolically "static" (no weight gain or loss).
Assuming an (unrealistic) diet of entirely sugar (for simplicity) - this translates to 561.25 grammes of glucose (1 gramme of glucose provides 4 kcal).
561 grammes of glucose is 3.118 moles of glucose.
During resporation, one molecule of glucose is broken down to 6 molecules of CO2. So 3.118 moles of glucose breaks down to 18.71 moles of CO2.
One mole of CO2 weighs 44 grammes, so 18.71 moles weighs 823.17 grammes, or 0.82317 kilogrammes.