The problem with chewing gum:

1. Whether chewing gum tends to stimulate or diminish appetite has not yet been clarified. There are hints to both directions. 

2. Chewing gum contains a number of synthetic substances that contradict the meaning of fasting. The aim of fasting is to relieve, detoxify and cleanse your body. So, chewing gum is counterproductive.

3. You should also reduce or avoid sugar and sweet drinks during the meal  periods - and then only enjoy directly after eating to calm your insulin  levels. This also reduces hunger attacks.

4. The same applies to sweeteners - these can throw your blood sugar  levels off track and cause increased hunger and discomfort.