I got a hold of that paper I mentioned a few days ago, and it's a dandy. It shows how the increase in added fats and sugars parallels the rise in obesity. The article actually tests three different hypotheses in the article: is the increase in BMI due to:
1) more fat
2) more sugar
3) more sugar and fat in combination
Both fat and sugar separately have high correlations with the increase in BMI, but fat and sugar together take the cake (pun intended!). Here's the graph:
They are getting R-squared's of 0.96, which is very high. Here's a few highlights from the paper:
"Other foods available for consumption such as dairy products, meat and eggs, vegetables, grains, and fruits were used as covariates along with fat and sugar production in multivariate regression analysis for male (female) BMI. For men, fat and sugar accounted for 96% of total variability in BMI (P < 0.001) with vegetables adding 1.5% (P < 0.001). For women, fat and sugar accounted for 97% of total variability (P < 0.001) with dairy (P = 0.0034), vegetables (P = 0.0145), and grains (P = 0.0191) each adding less than 1% to the total variability. Interestingly, dairy was negatively correlated with BMI (r = −0.86 and r = −0.90 for males and females BMI, respectively)."
In other words, they looked at the different food groups, but it was the added fat and sugar that was the primary determinant (like I mentioned in a previous post).
"The palatability hypothesis therefore predicts that increases in BMI are not due to calories per se in the drive system, but rather the increases are due to high levels of palatability that increase calorie consumption through increased stimulation of the incentive system. This leads to the hypothesis that the increased production of the additives of fat and sugar in combination would be most responsible for increased palatability and would therefore also provide the best mathematical fit for increases in calorie production and BMI over the last 30 years."
Here they are focusing on how fat and sugar in combination can produce palatable, addictive food.