His point is that "food science" is confusing and everybody is an expert who knows everything. Look at this discussion, for example. Every post starts with "The problem is..." or "No, the problem is actually..." Basically, everybody chiming in because they have it figured out
One person will tell you that eating whole grains is good, because they have complex carbs and fiber that will help you lower your cholesterol.
But then another person will tell you that whole grains are bad, because they have phytic acid which will rob you of nutrients and make your teeth rot.
Then someone will tell you that all you simply have to do is burn more calories than you consume, to create an energy deficit (and thus burn fat)
But then someone will tell you that your body will refuse to let go of certain fat because it acts as a storage device for toxins, so you need to cleanse with nutrient-rich food to lose weight.
One person will scream low carbs is the key.
Then another person corrects them, stating that simple carbs are bad, and complex carbs are good.
Yet another will state that fatty oils should be avoided, unless it's olive oil because everybody knows olive oil is healthy, just look how skinny the mediterranean people are!
This goes on and on. Everybody is an expert on health, and yet there's still obesity and health problems run amok. Personally, I think food is a very complex thing that we're not close to understanding. The best thing is to just eat like a dumb human animal, eating fruits, mushrooms, nuts and seeds, vegetables, whatever you can grab with your amazing human hands. Maybe occasionally, after lots and lots of running, you can eat some meat too.