Is it sugar directly that's bad for us or is it the obesity that's caused by sugar?

Refined sugar should be definitely limited at a minimum, not the only cause for obesity with lifestyle as important as food quantity and quality.

Excess intake of any food group is bad. Sugar intake is conductive to development of diabetes and obesity. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!

Normal intake of sugar is 150 calories a day for women ,or less and for men a little more than 150 calories. More sugar leads to diabetes, obesity and cavities .All are life threatening.

All things in moderation. Sugar is not a poison, but too much of anything should be avoided. Chlorine purifies water, but too much will make you sick. Oxygen is required for brain function, but too much can cause imbalance. Too much sugar involved in tooth decay, obesity, heart disease, stroke, etc. Eat a healthy diet and see your Physician & Dentist regularly.