A、Exercise only leads to modest weight loss without diet changes. B、Exercise can help people lose as much weight as they expect.

Most people who start working out in hopes of shedding pounds would be disappointed;(23)many scientists have found that without major changes to diet, exercise typically results in only modest weight loss at best.
     (24)To reach that conclusion, the Danish scientists rounded up a group of heavy young men. The volunteers, most in their 20s or early 30s, visited the scientists’ lab to undergo health check. None had high blood pressure or heart disease and, while heavy, they were not obese.
    The men were then randomly assigned to exercise or not. The non-exercisers returned to their former routines, with no change to their diets. A second group began 13 weeks of almost daily moderate exercise, consisting of jogging, cycling or otherwise sweating for about 30 minutes. A third group tackled a more intense routine of almost hour-long workouts.
    The men were asked not to consciously change their diets, and to keep detailed daily food diaries throughout the 13 weeks. At the end of the 13 weeks, the members of the non-exercise group weighed the same as they had at the start, which is hardly surprising. On the other hand, the men who had exercised the most, working out for 60 minutes a day, had managed to drop some weight, losing an average of five pounds each, about 20 percent less than would have been expected given the number of calories the men were expending each day during exercise.(25)Meanwhile, the volunteers who’d worked out for only 30 minutes a day did considerably better, shedding about seven pounds each.
23. What have many scientists found?
24. What do we learn about the experiment participants?
25. What do we learn about the result of the scientists’ experiment?