How body loses more fat in CO2 form than in sweating form?
If you exercise heavily, you can sweat enough where you have to drink to replace it. But on a normal day, you don't sweat all that much.
On the other hand, when you metabolize food, you essentially burn it. According to the Merck Manual,

Carbohydrates, proteins, and fats supply 90% of the dry weight of the diet and 100% of its energy. All three provide energy (measured in calories), but the amount of energy in 1 gram (1/28 ounce) differs:
4 calories in a gram of carbohydrate or protein

9 calories in a gram of fat


A typical diet is 2000 calories per day. If you get 50% of your calories from fat (shame on you!), that is 1000 calories of carbohydrate or protein, or 250 grams. It is 1000 calories of fat, or 111 grams. 361 grams total.
We will simplify. CH bonds contain little energy compared to CC bonds. H weighs little compared to C. We don't change much by ignoring H. There is some O and other stuff, but we will ignore that too. It will still be roughly right. So you burn about 361 grams of C.
For every C atoms you metabolize, you must breathe in 2 O atoms, and breathe out all 3 atoms as CO2. C atoms have an atomic weight of 12. O is 16. So CO2 is 44. Every 12 grams of C becomes 44 grams of CO2. So to burn 261 g of C, you breathe out 1324 g of CO2.
1324 g of water would be 1.324 liters. It is easily possible to sweat that much in a day, but you typically don't. You typically breathe out more CO2 than you sweat water.