"...The long term data clearly shows an increase in heart disease, atherosclerosis, diabetes, high blood pressure, and others that parallels the move to low-fat diets.
Bottom line: the low fat diet hype and scare is the greatest health epidemic of the last 50 years."
During the past seventy years or so four things have simultaneously happened here in the USA::
1. Increases in the aforesaid diseases.
2. Greatly increased rates of obesity in both adults and children.
3. Reduced physical activity by many people.
4. Increased consumption of food generally, including both lots more sugar than was previously consumed ("Don't you want to supersize that shake?") and also much more fat ("Fries come with that combo meal.").
Evidence is strong that increased obesity has brought with it lots of diabetes and other serious health problems. Inactivity, over consumption of carbohydrates, and over consumption of fats have apparently each separately contributed to our population's obesity epidemic.
Long distance hikers usually lose weight rather than gain it so, yes, there is much wisdom in the statement that "Fats and oils are extremely compatible with long distance hiking and provide greater energy to weight and energy to volume ratios than carbs." But, those of us who need to limit our weight while at home need to be wary of consuming too many calories from any source, including fats. At home its healthy for us to sometimes eat nuts, meat, and eggs, but not to excess.
I am wary of simplistic diet schemes that exalt or demonize "carbs" or "fats" or any other foods.