ConclusionExcess sugar consumption harms health in more ways than most realize. At the very least, it suppresses immunity and causes weight gain, two factors alone linked to many health issues, including increased cancer risk.
The problem isn't carbohydrates per se, because the body does need this food group. The big issues are overconsumption and consuming simple carbohydrates, which cause quick blood sugar elevation and increased insulin levels. Complex carbohydrates actually release simple carbohydrates into the bloodstream at slower rates and don't cause sugar spikes.
Sugary foods are definitely problematic -- and some form of sugar is hidden in most packaged foods and drinks. In general, natural whole foods are better than processed/refined foods because they contain other nutrients which regulate or mitigate the effects of sugar.
Everyone would do well to stay away from or at least reduce their intake of food products containing refined sugars and refined carbohydrates.