Pros And Cons Of Paleo, Keto And Fasting Diets

NEW YORK (CBSNewYork) - As we all gathered around the holiday dinner table this week and into the next, many people were talking about diets.

Visit the diet section of a bookstore and you'll see there are literally hundreds of diets out there.

CBS2's Dr. Max has a secret you may not know: They all work. You'll lose weight with all of them. The question is can you stay on them for life, and what are the health risks?

"All these diets aim to reduce the body's glycemic load," said Dr. Mitchell Roslin, chief of bariatric and metabolic surgery for Lenox Hill Hospital.

What Dr. Roslin means by that is most diets aim to lower that stimulate the body to make insulin, a hormone that essentially takes calories and locks them up as fat. Different diets try to reach that goal in different ways.

Here's how three popular diets do it:

THE PALEO DIET

With the paleo or "caveman" diet, the idea is to eat like our hunter-gatherer ancestors. It focuses on lean meats, fish, fruits, vegetables, nuts and seeds. It avoids grains like wheat, oats and barley. Beans, dairy products, sugar and potatoes are also no-nos. Experts say this is generally safe and effective.

"A paleo diet as practiced by most people has an over-reliance meats that can increase cardiovascular disease," says Dr. Roslin.

THE KETO DIET

A diet that's similar to the paleo diet is the ketogenic or keto diet. It's basically the Atkins diet of old, without the brand name. It's a very low carbohydrate diet. No starchy vegetables, pasta, bread, grains, fruit, dairy or sugar. Calories come primarily from meat, poultry and fish, which should all be lean. Instead, many people eat high fat, preservative laden meats like bacon.

Either way, the goal is to force the body to use fat instead of sugar as its main fuel.

"When glucose isn't available, it uses the breakdown product of fat called ketones," Dr. Roslin said.

Like the paleo diet, the keto diet works without much calorie counting, but it's very strict and hard to stick with and may be unhealthy, depending on your choice of meat.

THE INTERMITTENT FASTING DIET

The intermittent fasting diet has a lot of variations, but the newest trend means not eating at all for 14-20 hours, then consuming all your calories in a relatively short time window. Its health effect is to lower insulin levels.

"Hopefully decrease insulin resistance so you'll be burning fat tissue which is what you're trying to do," Dr. Roslin said.

Intermittent fasting also requires a lot of discipline to not eat when you're really hungry during a fast. Some people then overeat when they're off the fast, so they may not lose much weight, and big meals also include acid reflux.

Bottom line: The best diet is not a diet at all, it's a healthy lifestyle. Eat real food, not too much, mostly plants.