If you and your friend were jogging for 30 minutes at the same pace, and one of you sweat more than the other; who would have burned more calories?
Sweat is a natural phenomenon considered essential as it serves as a coolant for our bodies thus protecting us from overheating. It is mainly composed of water and few electrolytes. The volume of sweat can vary from one person to the other, depending on the number of sweat glands a person has and the ways they were activated. Perspiration can be induced by different factors, such as hot weather, higher body fat, intense physical activity, hormones, types of fabrics, etc.
Therefore, you should not consider sweat as a sign of fat burning or weight loss. Conversely you are encouraged to weigh yourself before and after the workout to determine the volume of water lost. Then, each half a kilogram of body weight lost requires the ingestion of half a liter of fluid to maintain proper hydration.