A nutritionist doesn't have extensive knowledge of biochemistry. A doctor should be a nutritionist. Disease is solely caused by damage to cells. That occurs via two routes. One is toxic overload/foreign bodies, and the other is deficiency. Deficiency occurs when an individual doesn't get the correct amount of nutrients in their diet. Toxic overload occurs through the pollution of air, water, personal hygiene/home/work products, and processed food. America is a nation of overfed and malnourished (nutrient deficient) people. The combination of deficiency in diet and toxic overload is what's killing everyone. Doctors attempt to cure disease. It only makes sense that they tackle the root of the problem.
I think most people are under the impression that fat/sugar resulting in weight gain is the main issue. Alone, it really isn't. Every human body needs those elements to be at their healthiest. The crux is that the body is unable to metabolize the chemicals that come with eating junk food.
Aspartame for example, eventually becomes formaldehyde inside the body. People that consume a large amount of this chemical are literally poisoning themselves over time. Numerous chemicals that cause disease are approved by the FDA all the time. Those chemicals go into many processed foods that people believe to be benign. It is most definitely killing people every single day.
I wouldn't say shock value is bad per se, because many people truly aren't aware of what is in the food and beverages they consume on a daily basis. Equating junk food with being obese, as opposed to the straw that breaks the camel's back in an environment where people already absorb pollution on every level, is more important than obesity alone. I believe a doctor is the best person to convey that message.