Help... My dad thinks I'm being unhealthy!

Hey guys. My dad is overweight, has type 2 diabetes, and is generally unfit. He half-heartedly tries to eat better (to at least justify himself), for example he buys sugar-free rice pudding, and then puts a large dollop of maple syrup on it (corn syrup! yuck!). Anways, that gives a bit of background on my dad.

Today I mentioned to him that I was interested in the paleo diet (/r/paleo), and I was going to try a variation of it (aka the not-too-extreme version) for 2 weeks to see if I liked it. I said that it was a low-carb diet, unless you ate sweet potatoes and a couple other starches. He said that was very dangerous, and that it was only for short-term weight loss, and not something I should be doing. He said I only need to lose at most 5 lbs (his definition vs my definition. I want to get defined (will take about 10-15 lbs with exercise), and he thinks that is unhealthy and as such doesn't support it.

I can buy my own food and store it, but since I live in the same house he will constantly disapprove.

What can I do to get him to see that me being ripped isn't unhealthy? I can't teach an old dog new tricks and get him to stop eating like shit and see the light, but I don't want him breathing down my neck because I have decided to try and better myself.

Thanks for any and all tips!

edit: grammar. derp.