7. The following appeared in the health section of a magazine on trends and lifestyles. People who use the artificial sweetener aspartame are better off consuming sugar, since aspartame can actually contribute to weight gain rather than weight loss. For example, high levels of aspartame have been shown to trigger a craving for food by depleting the brain of a chemical that registers satiety, or the sense of being full. Furthermore, studies suggest that sugars, if consumed after at least 45 minutes of continuous exercise, actually enhance the bodys ability to burn fat. Consequently, those who drink aspartame-sweetened juices after exercise will also lose this calorie-burning benefit. Thus it appears that people consuming aspartame rather than sugar are unlikely to achieve their dietary goals。 Discuss how well reasoned . . . Etc.
The article concludes that it is better to use sugar than the artificial sweetener aspartame for those people who want to lost weight. The author uses two reasons to support his viewpoints. First, high levels aspartame will cause people to eat more. Second, sugar can help fat-burning if used properly. These reasons can only tell reader that aspartame has some bad side-effect while sugar has some good effect, but they cant prove that sugar is better than aspartame for weight-control. Therefore, the reasoning is less than sufficient and the argument is not convincing。