High Protein Diets (including South Beach, Atkins, and Bernstein): the most aggressive of these is Atkins; the key of all of them is the ratio of very high protein to very low carbohydrates.
- Benefits: This approach is effective for lowering cholesterol, triglycerides, insulin resistance and blood sugar, and weight.
- Problems: Too much protein over a period of time can lead to kidney damage, weight loss, and (depending on the type of protein consumed) high saturated fat relative to essential fatty acids. It can also set you up for nutrient deficiencies if your primary source of nutrition is meat. Also, your body runs on glucose from carbohydrates, not protein – so although it is possible for your body to turn protein into energy, it’s not nearly as efficient, so you may feel exhausted. And finally, lack of fiber may lead to constipation. I wouldn’t recommend this approach long-term.
High Carb, Low Fat Diets (including Ornish, Pritikin, McDougall, and Swank Diets): for these, complex carbohydrates (such as fruits, veggies, and whole grains) comprise 55% or more of the diet.
- Benefits: Like all plant-based diets, these will lead to lower cholesterol and triglycerides, weight loss, lower cardiovascular and cancer risk, and a healthier gut due to the high fiber.
- Problems: These can set you up for deficiency in essential fatty acids (since those are fat), and in fat-soluble vitamins (A, D, E, and K). Some people also feel inordinately hungry, and potentially hypoglycemic.
The Vegan Diet: this removes all animal products, and is entirely plant-based: whole grains, fruits, veggies, beans, and nuts.
- Benefits: Popularized by “The China Study,” this diet will lower cholesterol and triglycerides, and lead to weight loss, lower cardiovascular and cancer risk, and a healthier gut.
- Considerations: I am not convinced that the reason for the above improvements isn’t because most sources of animal products are agro-industry; all animal sources are not inherently bad. The fats in agro-industry animal products are almost entirely saturated, while grass-fed and free range meat and animal products are around a 50/50 ratio of saturated fat and essential fatty acids (the latter are highly anti-inflammatory and cardioprotective). Some sources suggest that the reason saturated fats are associated with inflammation is not due to the saturated fat itself, but rather due to the relative deficiency of EFAs.
- Problems: Some people do well on a vegan diet as long as they are vigilant about protein intake and supplement with vitamin B12 (which is found almost exclusively in animal products), but others feel chronically hungry and low in energy. It’s also possible to eat a “vegan” diet that is almost entirely comprised of processed crap and a whole lot of soy. Make sure if you’re going to do it, that you’re eating real food.
The Mediterranean Diet: this one includes fresh fruits and veggies, whole grains, nuts, seeds, legumes, seafood, yogurt, and small amounts of wine.
- Benefits: It’s considered heart-healthy due to the fact that it eliminates most sources of saturated fat (see the discussion above).
- Considerations: You need some saturated fat in your diet to be healthy – this diet is healthy, it just might be unnecessarily restrictive.
The Paleo Diet: This one includes lean meat, fish, veggies, fruit, roots, nuts/seeds, and eggs. It excludes legumes, grains, dairy, salt, refined sugar, processed oils, alcohol or fermented drinks.
- Benefits: This is a clean diet, and also it removes two of the most common allergens (gluten and dairy).
- Considerations: I don’t think it is necessary for non-sensitive individuals to cut out gluten and dairy – although most people will feel better when they do, because gluten and dairy are generally present in most highly processed foods. However, gluten-containing whole grains and raw or organic milk and dairy products will not bother non-sensitive individuals. I don’t see any reason to cut out legumes either, except in some individuals who feel bloated with them. But all things considered, this is probably my favorite of the “fad” diets.