Diets. They work for some, but not for others. "You're just not on the right diet," purveyors of the latest trend will tell you. "You're just not on the right diet for your blood type, ethnicity, age, hair color," says another set of true believers.So what's right and what's wrong? Today on Fork U, a conversation between Dr. Terry Simpson, weight loss physician, and Dr. Bill Lagakos, nutritional biochemist and physiologist, where they expose the truth behind diets and why they may, and may not, work for you. And check out Bill's book, The Poor Misunderstood Calorie.TRANSCRIPT:Terry Simpson: Bill, there are a lot of weight loss programs out there. The one that I'm hearing the most about most often is the Keto movement, which says that they're going to cure everything from heart disease and cancer. Bill Lagakos: I think from a 30,000-foot view, Keto works for a lot of people. So does low fat. I like some of the recent work, the studies showing it's more about the level of processing of the food.So you can have a vegan diet or you can have a Ketogenic diet and as long as it is excluding a lot of processed foods, it tends to not be over eaten. And people that tout the magical benefit effects of any of these diets, 99% of the time it's due to weight loss. Terry Simpson: We actually had an experiment with Evo, who you met. He uhh did it several years, three or four years in a row for one month, Evo would go on a beer and sausage diet, rigorously kept his calories to 1500. We measured his liver function tests, his lipid panel. Every year he lost weight, kept it off, and every year his liver function was fine, surprising with the number of beers he had a day, which was limited to six. But it was, he had weight loss and he had sustained weight loss over the year with a, kind of this funky diet we sort of made up. Bill Lagakos: Well, that's terrific. And that's an awesome diet. I'm jealous. But, uh, yeah, that, that basically proves the point. I mean, even if it's not a lot of weight he lost, I think a weight loss is a major driver in a lot of the health improvements that people like to attribute to particular dietary trends. Terry Simpson: There doesn't seem to be a lot of long-term data in these diets. When I look at the sort of metadata, I see that if you eat really high on the low-fat side, you have a little lower lifespan. If you eat really high on the high-fat side, you have a little lower lifespan. If you have your carbs at about 55%, you seem to have a little longer lifespan. Is there much good data saying one diet versus another, other than the Mediterranean, has great long-term results?Bill Lagakos: I don't think so. I don't think it comes down to macros at all. I think that there's the confounding in those studies is so deep that I don't think the macronutrient composition of your diet is going to be what kills you in the end. Terry Simpson: Part of your job is helping people lose weight. What are sort of the big messages you try and get through to people?Bill Lagakos: One of the biggest things is the importance of adherence, which is why I try to say, you know, what do I know that, that you can adhere to 100%? It's what you've been doing because you've been doing it. So let's try and find the lowest hanging fruit that we can change so it doesn't turn your whole world upside down, which is something that would probably never work.Terry Simpson: So in other words, you're not going to change a Keto into a vegan or a vegan into a Keto....