If you want someone to be courteous about your choices then it is best to model that politeness and not answer a rude intrusive question with rude intrusions upon his personal life.

I would suggest you say something like "I am glad you enjoy what you eat! I eat this way because I enjoy the food and I enjoy the way I feel when I accept this pattern, but I understand it isn't for everyone. Please understand that it is the choice I have made for myself right now and I appreciate you supporting me choosing what works for me. I will support you making the choices that work for you."

Uninvited proselytization is, to my mind, always rude. And it feels terrible. I am sorry you had to experience it, but it does seem to a lesson that more people in the paleo community could stand to learn.

I hate to say this, but my sister-in-law used to brag all the time about eating candy bars and Diet Cokes for meals, talking about how lucky she was that she never got fat. Truthfully, for many years she was a beautiful, shapely redhead who appeared pretty fit. Now, about 30 pounds, ten years, the loss of her gorgeous long red hair and four chemotherapy treatments later, she is starting to listen to my advice regarding Paleo nutrition. It is nice to be 25 and think the basic rules of biology don't apply to you. But the earlier you can educate yourself and implement what you have learned, the longer and happier your life will be. Just one person's opinion...

Trust me, the effects will show long before 50. However, there is nothing you can really say. "Youth is wasted on the young". I just turned 42 and my teenage sons still can't catch me! Recently and arbitrarily, I ran into quite a few old friends in my age range. Two of which, were quite accomplished athletes. I am saddened to say that 3 out of 3 are 60 lbs overweight on average, Type 2 diabetic, one has glaucoma and high blood pressure, and all are arthritic. One to the point, that it takes him a considerable amount of time to navigate stairs. Whats scarier is that you can see these negative health effects creeping in at much younger ages.

As far as running 15-20 miles per week, that's only 2-3 per day. That's far less physical work than what a professional athlete does or something like that.

If you look into some of the research from guys like Dr. Lustig with fructose, you'll understand he's doing damage to himself whether he knows it or not. Check out his video, "Sugar: The Bitter Truth," on YouTube to understand more about sugar.

Also, sometimes obesity is a warning signal for folks to know that what they're doing is harming them. Sometimes I feel bad for people who don't get this warning signal and then they become diseased much earlier in life from their poor lifestyle choices.

As far as consuming a lot of fried food, look up some of the stuff on the dangers of PUFA (polyunsaturated fatty acids). You can find good information on a lot of blogs (e.g. Daily Lipid, Archevore, Mark's Daily Apple, etc).

As far as grain consumption, I'm under the impression that many younger adults can tolerate them to a point. He's probably still within that limit. I also believe that eventually most will begin to show negative signs of grain consumption. This is a big more complicated though since it involves an evolutionary perspective.

Anyway, I'd watch that video and read up on the PUFAs. That should give you some good information if you want to talk to him about it although it sounds like your words might fall on a pair of deaf ears.

What you eat is not his concern and has no effect on him whatsoever. He sounds very immature, hopefully one day he'll wise up before it's too late.

When I hear about people like that, I feel grateful for all my allergies and sensitivities. I used to think they were weaknesses, but really, they're forcing me to make better decisions at a relatively young age. It's humbling to realize how fragile your life is. Sure your co-worker feels invincible, but he's not. No one is. All we can do is try to be better than we were yesterday and set an example for others that care.

Some people aren't affected so much by carbs. I know several people who can eat it regularly without getting fat, however most of the carb-loaded foods are usually very low in nutrition, so it's easy to get nutrition deficiencies without even being aware that you have them. One only notices the deficiencies upon test, or when recovering from them. For his age, that is probably the biggest risk. The rest might come (hopefully not) when he is older.

I don't know why he would think your food choices as stupid however. McD's meat isn't even the best or yummiest, so I don't know exactly what he likes about it hehe

It might be best to leave him be, however frustrating.

When I was in my 20's, I hated it when people ~20 years older than me would give me advice telling me that I was a young'un. But I'm 41 now so I'm afraid I'm going to do the same thing...

When you're in your 20's and healthy you can probably eat virtually anything without feeling any ill effects, and the same can be said about drugs and alcohol... abuse of your body doesn't really start to show up until your 30's and definitely in your 40's.

I don't think it's totally a coincidence that many rock and roll musicians died at the age of 27... right around the time when their abuses start to catch up to them.

Smoking is maybe an even better example, you can smoke for 20-30 years without feeling any ill effects, but then you're very likely to die.

So your co-worker can stuff himself full of junk food and feel fit, but in probably 5 years he'll start to have issues and will go into a dietary crisis. Of course that doesn't do anything for his bragging rights now...

Don't say anything in rebuttal to his comments. It's called the high road, and there's no traffic up here...

Have you ever heard of the book 'How To Win Friendsand Influence People' by Dale Carnegie? It's a pretty great analysis of typical social interaction. A key point of his is that there is minimal positive outcome to showing a person the err of their ways. Think about it. Pretty much he won't believe whatever you tell him. On the off chance that you do can prove you're making better choices than him, guess what that makes you in his eyes? The person who ruined his party or added guilt to his favorite foods.

Basically, why bother? You'll be much more satisfied in the end if you just smile & nod. Maybe join him at making a few jokes about your own food. Self-deprication takes the wind right out of the average smart-ass.

the only reason i dont eat fast food is cuz of fear of that crazy moo moo disease