Lipogenesis is the process by which new fat is created. Individuals seeking the latest cheap "fat loss secret" may not be particularly in the mood for a deep discussion of hormones and biochemical mechanisms. But in order to understand the alternative hypothesis of why we get fat (i.e., the Lipophilia Hypothesis), we need to look at what's driving lipogenesis.
According to the Caloric Balance Hypothesis (the mainstream idea that excess calories make us fat), the problem obese people have is that they overeat and they don't get enough exercise. In other words, there's something psychologically defective about them. They can't control their appetites. They don't have the willpower to go to the gym. Obesity and overweight result from a character defect.
The Lipophilia Hypothesis instead suggests that the defect that causes obesity is in the body, not in the brain. Hormones regulate lipogenesis. Specifically the hormone insulin.
Journalist Gary Taubes explains on page 295 of Good Calories, Bad Calories that obesity researchers will readily admit that hormones and metabolic factors will influence how tall we get via their effect on the growth of muscles and bones, and that these hormones will drive the body to find/hoard the necessary calories to make us taller. But these same researchers "see no reason to believe that a similar process drives the growth of fat tissue."
So where does that leave us?
Once again, we have two hypotheses, and we have two very different predictions for how the world should work.
On the one hand, the Caloric Balance Hypothesis tells us that the problem with overweight people is that they can't control their behavior.
On the other hand, we have this other hypothesis that tells us that weight gain is hormonally driven -- it has nothing to do with conscious regulation of behavior at all.