Normally I do not participate in internet Forums or discussions unless something is that close to my heart. When someone had posted in a scientific forum that Sugar is the cause of Obesity, I couldnt post the following as a rebuttal: Hope you agree with me.

In the USA, I work exclusively with Native Americans. A group of people who were all lean, in 1908, (their last year of freedom among the Lakota was 1862) are now 95% overweight or obese. So just to say it is calories and lack of exercise would omit many other factors.
I can send you a graph of whether "sugar" consumption has increased or decreased in the USA. It has decreased since 1970 but what has increased is the intake of artifical sweeteners such as High Fructose Corn Syrup and also Maltodextrin, Glucose, Aspartame etc. 

It has been shown that one can a day of Diet Coca Cola over the years can lead to Metabolic Syndrome which is a precursor for Diabetes Type 2.

  30 per cent of americans are overweight, 30 per cent are obese, the most overweight countries in the world (except some polynesian islands) are : UK Australia New Zeland and Canada.  The middle eastern countries such a Kuwait and Qatar (which may have gained no 1 spot if you count only Qataris who make up less than 25 per cent of the population of Qatar, the rest of them being indentured workers from the west and the east and africa and other arabic speaking countries).  I am aware of the situation of Diabetes and Heart Disease in many asian countries: India is the capital of Type 2 DM and the highest rate of heart attacks for men under the age 40 in the world, China is not far behind, the other member of BRIC countries  Brasil also has high rate, the reasons in these three countries may be the same. I have seen at least 40 normo glycemic, normocholesterolemic, normo BMI (less than 23 kg.m2)  and very active (by podometer readings at least walking 5 miles per day) with  four vessel bypass surgery in Bangalore India. The rate of Diabetes in thinner Malaysians of Indian origin is greater than the overweight Chinese in both Malaysia and Singapour. Cambodia which has a very high rate of Diabetes type 2 has no problem with obesity. One has to consider the genocide they suffered under Khmer Rouge and the stress that was put on that society since most of the new type 2 DM are under the age of 40, who were either born during khmer rouge or soon after that.

So it would be difficult for me to accept that there is just one reason which is non biochemical to explain the obesity, diabetes etc in various population. The oppression , colonization, joblessness and hopelessness among the American Indians have a lot to do with their obesity, insulin resistance (like many indigenous peoples their insulin levels are high to begin with starting at age 7) and Diabetes. 
I also have a graph showing sugar consumption and rate of diabetes in 25 different countries and there is no correlation. Once again what do we call "Sugar"?
Regarding nutrition and fat, i would consider every day american food to be one of the worst in the world. If we are just going by fat and cholesterol of the food content, the French who eat five couse lunches and dinners have half the rate of americans when it comes to diabetes and heart disease compared to USA, which is popularly referred to as the French Paradox. 

Americans consume about 100 pounds of chemicals per year in various forms and i am sure that BPA which is stil  in use and the multides of Endocrine Disrupting Chemicals in that country may explain some of the differences in their high rates of Thyroid Dysfunction, Lowering levels of Testosterone, High levels of Precocious puberty among others. 
Greetings to all of you, my colleagues from La Habana, Cuba where we could prove that Anxiety about Food alone was responsible for the rise in obesity when suddenly the food supply diminished after the fall of Soviet Union. and Cubans are not sedentary people. We dance almost every day. Bienvenidos..