He'd never promote unhealthy things, but the secular society promotes unhealthy fads. Like, some promote esotery or occult, yoga and karate are "cool". If Jesus Christ chose wheat, then must be a reason for it. But the devil never sleeps and tries every means to attack Jesus, the Church, Eucharist, etc. Then you should reject the Paleo, and even the gluten-free fads. I think that Jesus has more power and could do more than watching people losing their communincablity. Many have lost their opportunity due to the post-concilliar shift. But what is the point of living in Trad Land when a disease bars you of Communion?
The problem in our time is the sedentary lifestyle, which leads to obesity, which is why diabetes is everywhere. Grains would not be a problem if people actually moved like they used to, walk instead of drive, do manual labor, etc.
When people eat food that spikes their blood sugar, things like grains, rice, breads, pasta, it turns into glucose. If people are not moving and burning it off, it will lead to weight gain and the body must produce more insulin to deal with the sugars in the blood.
So, grains are not bad in and of themselves, but if you eat foods that are high on the glycemic index, and you live a sedentary lifestyle, you are setting yourself up for weight gain and diabetes.
The Paleo and Primal diets do work and are especially good for controlling blood sugar levels. They may even be enough for type 2 diabetics to stop or reduce their medications.
By saying that I am not anti-grain. Grains are a gift from God to mankind, because they are easy to grow, easy to store, and have a very long storage life. They are the perfect food for famines as the Bible teaches us, remember the story of Joseph.
But, when you eat a diet with grains, just remember to move around a bit, take a walk, work on the garden, or whatever else to burn off the sugars.