Glorifying God with Your Body or Cultural Obsession?

I have been seeing some form of this message for years.
It goes something like this: "Our bodies are the temple of the Holy Spirit, therefore, we should glorify God and achieve the 'best' body we can."
This message then is typically accompanied by diet plans, exercise regimes, and, of course, "motivating" before and after photographs. Often this message promotes the idea that because we have been given a body by God and that body has become His temple then we should glorify God by striving to be as "healthy" as possible (read: fit, lean, strong, etc.).
I saw yet another of these messages the other day and as I was skimming over it I found myself almost verbalizing out loud: "But what if the best temple someone can and should achieve is just 'average'??"
Seriously.
I am not sure I understand at what point it was determined that God expects His temple to have flat abs, toned arms, and fit into a smaller pair of jeans? I am not sure I understand at what point it was determined that God expects His temple to be sugar and GMO free? I understand our bodies, the temple, should be treated with respect and care, which includes tending to our bodies with nutritional food and adequate exercise. But somewhere along the line the agenda of the diet and exercise industry got intertwined with a Christian message and the damage can be (and I think already is) extensive.
Here's the truth: God is not asking us to glorify Him with our bodies by achieving a certain body shape, weight, or size. We do not have a better temple if we lose X number pounds or build a certain amount of muscle. Nor do we have a better temple if we only eat organic and cut out sugar.
Superficial body and behavioral changes in of themselves is not what He is after. He's after our heart. And quite honestly, for some people striving for things like weight loss and cutting out sugar is actually less glorifying to God then eating the piece of cake and not losing a single pound (or *gasp* actually gaining some).
So instead of focusing on changes in our bodies, we have to do the harder work of the heart. Examining our relationship with food and our bodies. Taking note of our motivations and core beliefs. Confronting our unhealthy coping skills. Challenging our idols and what we worship. And our bodies will follow (if they even need to change at all).
Just please stop believing the lie that a better temple looks and behaves in a way that actually is more reflective of our culture's obsession with diet and exercise instead of the heart of our Father who loves to make our hearts His home.