Well yes many things are.
Coronary heart disease Type 2 diabetes Cancers (endometrial, breast, and colon) Hypertension (high blood pressure) Dyslipidemia (for example, high total cholesterol or high levels of triglycerides) Stroke Liver and Gallbladder disease Sleep apnea and respiratory problems Osteoarthritis (a degeneration of cartilage and its underlying bone within a joint) Gynecological problems (abnormal menses, infertility) Knee and joint problems Gastric reflux, many forms of psoriasis
No, that is incorrect. Some (but not all) of these conditions are associated with obesity. Correlation does not prove causation. Many of these conditions have a strong genetic link, and believe it or not, there are plenty of slender people with hypertension, cancer, gallbladder disease, and everything else on your list.
These studies set out to get certain results. No one should be surprised when they get what they want. It keeps the funding flowing.