[求助]帮我看看这个题目的意思，谢谢！

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 body’s 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.”

主要是第一句话不理解，什么是better off?怎么解释第一句话，快考了，谢谢帮助。

但后面说的内容都是蔗糖比代糖好，怎么回事？

你看第一句话后面since的内容，立刻说了蔗糖比代糖好，还说是前面一句话的原因，真的是搞糊涂了。

整个论证是什么结构？尤其是第一句话（红色的），后后面的论述什么关系？