Ribose is metabolized very differently than regular sugar and actually has a negative glycemic index, meaning that it likely causes weight loss, not weight gain.
The problem with ribose metabolism is that people with low energy production have trouble making enough ribose or holding on to it. Taking the ribose directly solves these 2 issues. In others, the problem is in making energy. Higher levels of ribose help move the energy producing reaction forward. Because of this, taking ribose actually helps solve problems with ribose metabolism.
What we do see (present in 2 of 41 people in our ribose study), is that some people get overly energized and hyper from taking ribose. This manifests as feeling hyper or as low blood sugar symptoms. These symptoms go away by simply taking the ribose with food or lowering the dose. It has also, in my experiences, been a marker for when people need adrenal support (adrenal function maintains blood sugar levels - when symptoms of low blood sugar occur, this suggests the need for adrenal support). The ribose can then be especially helpful in the healing process. But these side effects are a sign that one also needs nutritional adrenal support. This can help improve energy and improve overall health in those with symptoms of low blood sugar.