The phrase ‘working up an appetite’ can apply to manual labor as well as physical exercise. Overweight people wanting to get into shape and lose weight might worry that the work they put in at the gym might increase food cravings. A study published in the journal Medicine & Science in Sports & Exercise compares the effects of steady state and interval training on obese subjects.
 

Researchers assigned 46 inactive obese subjects (30 women and 16 men) to 12 weeks of moderate intensity continuous training or high intensity interval training. Both groups trained 3 times a week. Feelings of appetite and hunger hormones were measured before and after the exercise intervention, and also before and after a standard breakfast. Although feelings of hunger increased with exercise, there was no difference between steady state and HIIT groups.