What do you do when you see someone promoting a fad diet?

Elina, that's my point; I hear people swear that if they eat ONE Twinkie, it will keep them from losing any weight at all! Or that they counted honestly, and only ate 800 calories, but half of it was carb, and they gained half a pound.  That's the 'carb sensitiity" I don't believe in. I incidentally feel very badly for people when they post about feeling tremendous guilt for eating one cookie or a bite of ice cream, assuming the amounts are truthfully stated. That kind of guilt can make you try to heaI yourself with fat and sugar!  I do agree that if you have a "sweet tooth" or love fries, you had better be very, very careful if you do eat them. I DO have a sweet/tooth, so my little snack is one of those 1 oz chocolate squares or one of the smallest bag of Cheetos, I don't buy but the one piece/package, and it has to come inside the house before I eat it. (And I have a very old and not overweight cat who gets part of the Cheetos :P)

 Doesn't really matter if you believe in it or not, its a medical fact that some people process carbs diffrently. 

I would believe it if I saw some actual scientific research that proved it, but have never seen any to support this. I'm not talking about things a nutritionist, personal trainer, or author says, but actual studies. I've never seen any, and I have tried to find them.

Try looking up PCOS or Insulin Resistance. I live it every day, it's not something a trainer told me, its a medical condition that I LIVE with, diagnosed and treated by a MEDICAL DOCTOR (after almost 15 years medicated to control it). Carbs effect blood sugar levels, which effects how the body makes, burns  and stores body fat and calories. 

I did not mean to imply that you can't process carbs in a different way, and I am familiar with insulin resistance. My post was not directed at anyone with a medical condition, and I'm sorry if it seemed that way! It WAS directed at the idea that 'carb sensitivity" is something that can make you not lose any weight even on minimal calories, or that if you eat say 6 oz of carb it would be the reason for a sudden weight gain of a pound or more. Obviously there are metabolic or endocrine  disorders that effect rate of weight loss or gain, but 'carb sensitivity" in the sense it is generally used by those on an Atkins or other type plan is the thing I don't believe in. heck the original Atkins diet is in fact a low calorie diet, which is why it's good for so many people with a big appetite. Eating 1500 calories of just meat is HARD! And as we all know, eating 1500c of carb is far, far, too easy.
Back on topic, I have a friend who goes on an 'apples and oatmeal and green tea' diet to drop a few pounds on occasion. It's not the most unhealthy ever, but she seriously thinks those three things together 'do something' to make you drop weight fast if you don't eat anything else. I call the 'something' it does being full, because who can eat 2 appless and a cup of oatmeal and still fit anything else in, but whatever!

One of the conclusions that I have come to in the past year is that it is not my job to fix the world, or anyone in it other than myself.

If someone specifically asked me my opinion about a fad diet, I would give it.  Otherwise, I would keep my mouth shut and wish them well.