If Excess Calorie Intake Causes Obesity, Why Does Obesity Associate So Closely with Other Diseases?
Calorie intake and expenditure determine how fat we get, according to the Caloric Balance Hypothesis. And getting fat puts us at risk for a smorgasbord of health problems, like Alzheimer's disease, gout, heart disease, type 2 diabetes, stroke, and depression.
But how exactly does gaining weight cause us to be at risk for these diseases? And how does losing weight cause us to be less at risk? Does excess calorie intake cause Alzheimer's disease, gout, and so on? And if so, how?
What are the biochemical mechanisms that show precisely how "excess calories" drive us to get these other diseases and how a deficit of calories somehow fixes them?
The Caloric Balance Hypothesis gives us no answers. It tells us nothing.
If you blame obesity on a "positive caloric balance" (a.k.a. eating too much and not exercising), you can't explain the associations between obesity and the diseases to which it seems to predispose. Not only can you NOT explain the associations -- but you certainly can NOT say anything at all about what's causing what.
Why this is such a big deal.
Typically, when good scientists note that a variety of factors associate, they look for reasons why such associations might exist. Could one factor cause all the others, for instance, or could they all share the same as-yet-to-be-identified root cause?
Good scientists separate correlation from cause. When a variety of factors associate, they're very careful before pronouncing what causes what.
And yet somehow, when our health authorities note that we're overweight, they assume that controlling our obesity by cutting calorie intake and going to the gym will therefore protect us against diseases. This is perplexing.
Consider this analogy. Imagine you come to a doctor with a high fever, runny nose, sore throat, earache, and a rash. Other patients complain of similar symptoms. The doctor would no doubt extrapolate that perhaps you've got a virus or infection -- a root agent driving all of these symptoms. You might be prescribed bedrest or an antibiotic. The doctor probably wouldn't order you to take an ice bath to bring down the fever, figuring that curing the fever will fix the other symptoms, too. He or she would have the good sense to realize that the fever wasn't a cause but a symptom of an infection or virus.
But go to a doctor complaining of obesity, and you'll be told to cure your weight problem in order to prevent other problems/diseases. A causal relationship is just assumed. Why?
If obesity turns out to be a manifestation of a deeper metabolic disorder, this presents a big problem for the Caloric Balance theory.