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 NOTE: As a Registered Dietitian, I work with individuals to find a healthy balance between food, exercise, emotions, and life. I do not condone "diets," but often get asked about them. This post is not intended to encourage a particular eating pattern, but simply to inform. Please share your thoughts/questions in the comments section. 

Paleo Diet

The Paleolithic diet (ie, Paleo diet) emphasizes eating foods that those who lived during the Paleolithic times, some 10,000 years ago, consumed. Humans previously consumed only wild and unprocessed foods; therefore, their diet was high in lean proteins, monounsaturated and polyunsaturated fats, fiber, vitamins, minerals, antioxidants, and other phytochemicals. Some have suggested that this type of diet falls more in line with human evolution than a cereal-based diet, which may explain the lower incidence of chronic diseases such as type 2 diabetes, obesity, and cardiovascular disease among hunter-gatherers.

Walter L. Voegtlin first made the Paleo diet popular in the 1970s; since then, numerous authors and researchers have revised and recreated it. Its focal foods are meat, fish, vegetables (excluding potatoes and sweet potatoes), fruits, roots, and nuts (excluding peanuts and cashews). It disallows grains, legumes, dairy products, salt, flours, refined sugars, and processed oils, all of which became available only after the development of agriculture. The Paleo diet is approximately 19% to 35% protein, 22% to 40% carbohydrate, and 28% to 47% fat.

CrossFit, a core strength and conditioning program that has been gaining in popularity, encourages participants to follow the Paleo diet.

Pros: Some scientific studies have revealed health benefits associated with the Paleo diet. Frassetto et al found that even short-term consumption of a Paleolithic-type diet improved blood pressure and glucose tolerance, decreased insulin secretion, increased insulin sensitivity, and improved lipid profiles without weight loss in healthy sedentary humans.

The diet focuses on eating animal proteins and foods that come from the Earth rather than processed foods, supports “clean” eating and consuming whole foods, and is very satiating due to its high fat and protein content. In addition, much of the fat consumed on a Paleo-type diet is heart-healthy monounsaturated and polyunsaturated—especially omega-3—fat.

Cons: The diet:

• is restrictive, disallowing many foods, including pasta, bread, potatoes, and desserts;
• some may have an initial “withdrawal” period due to eliminating coffee, sugar, alcohol, and refined carbohydrates;
• may not promote adequate calcium and carbohydrate intake; and
• is high in fat.

Bottom Line: The Paleo diet steers followers away from processed foods and encourages clean eating, but it may be too low in carbohydrate and calcium and too unrealistic/drastic for many people. Additionally, in Paleolithic times, people were much more active than most are today, which may have contributed to the observed reduced incidence of disease.

Raw Food Diet

Followers of the raw food diet consume primarily uncooked, unprocessed plant foods. The main food components of the diet are generally fruits, nuts, seeds, sprouted grains, and beans. There are several variations of the raw food diet and there is no general definition.

Proponents claim that if followed correctly, the diet leads to a leaner body, clearer skin, and increased energy. These claims are based on the theory that in their natural state, plant foods are more wholesome for the body. Raw food proponents believe that heating any food above 116˚F destroys important enzymes that aid digestion and absorption of essential nourishment.

Pros:   People following this diet generally eat a great amount of fruits and vegetables, which are rich in nutrients and fiber. Research has shown that people consuming a plant-based diet usually have lower levels of cholesterol and triglycerides. Additionally, it is true that overcooking foods can have negative effects, such as reducting nutrient content or producing hazardous byproducts (such as acrylamide, which is produced when starches are cooked at very high heats for too long).

Cons:

• Because a raw food diet lacks variety and animal proteins, it may promote vitamin B12 deficiency, which can lead to anemia and neurological problems, and lower bone mass.
• A study published in the Journal of Nutrition found that while this diet may lower total cholesterol and triglycerides, it may also lower high-density lipoprotein cholesterol and increase homocysteine concentrations due to vitamin B12 deficiency. Elevated homocysteine is considered an independent risk factor for cardiovascular disease.
• Overall, this is not an easy diet to follow. It requires much preparation and organization and can limit one’s ability to enjoy meals socially.

Bottom Line:  While a diet rich in fruits and vegetables is certainly beneficial to one’s health, raw foodists purport some extreme views about cooking food that lack scientific merit. Eating raw fruits and vegetables is great, but eating raw meat and fish can expose one to excess food safety risk. Plus, this diet greatly limits ones ability to eat socially.

Baby Food Diet

This is one of Hollywood’s latest diet crazes, with some well-known celebrities reportedly following it. The diet involves eating jars of baby food to limit portions and restrict calories. Followers either eat baby food as a snack to curb hunger or substitute other foods with one or two jars of baby food—an average jar of baby food is 15 to 110 kcal per serving—at lunch or dinner.

Pros:  Baby foods are generally rich in nutrients, free of additives, and portion-controlled. Organic varieties are also available.

Cons:

• Small portions and restrictive dieting can lead to binges.
• Baby foods taste bland.
• Calorie intake may be insufficient for the day, depending on the number of meals substituted for baby food.

Bottom Line: Although baby food is a nutrient-rich food option, limiting oneself to a jar or two of baby food for a meal is a very restrictive practice for an adult. Caloric restriction is more likely to induce binge-eating behaviors.

Apple Cider Vinegar Diet

In the 1950s, Dr. D.C. Jarvis wrote Folk Medicine, which set the stage for apple cider vinegar as a weight-loss agent.1 Jarvis claimed that regular consumption of the tonic would cause the body to burn fat rather than store it. Other proponents have claimed that the pectin in the vinegar binds and removes cholesterol from the body.

Supporters say that consuming 1 to 3 tsp of apple cider vinegar 15 minutes before each meal will aid weight loss. The apple cider vinegar diet does not prescribe a menu or meal plan but recommends eating in moderation and skipping snacks. Proponents suggest that over time, the vinegar will decrease hunger and cravings.

Pros: Apple cider vinegar is inexpensive. Additionally, a small study published in Diabetes Care in 2004 found that vinegar significantly improved postprandial insulin sensitivity in insulin-resistant subjects and possessed physiological effects similar to acarbose or metformin, diabetes drugs that help control blood glucose. However, further investigations into the efficacy of vinegar as an antidiabetic therapy are warranted.

Cons: Currently there is no solid evidence to support the use of apple cider vinegar for weight loss or other medical purposes. According to WebMD.com, consuming 8 oz of apple cider vinegar per day may lead to long-term problems such as low potassium and osteoporosis. And although at least one trial showed possible benefit to those with diabetes, WebMD.com suggests that long-term use or high doses of apple cider vinegar might increase potassium loss in people using insulin. In addition, apple cider vinegar:

• may cause stomach and throat irritation due to its acidity;
• may cause bone loss when used long-term;
• may interact with other medications; and
• has a pungent taste.

Bottom Line: Some research shows that supplementing the diet with apple cider vinegar may have some health benefits, such as improving blood glucose control. But, since there are several potentially serious risks associated with its consumption, consumers (especially those with conditions such as osteoporosis or who take certain medications) should exercise caution.

Grapefruit Diet

This diet has existed since the 1930s. According to grapefruit-diet-plan.org, eating lots of “fat-burning” grapefruit will kick-start metabolism. The plan lasts for 12 days, and according to the Web site, if people practice it correctly they can lose up to 10 lbs.

There are several variations to the grapefruit diet plan, but the principle behind each is the same: Eat one half of a grapefruit before every meal to trigger fat-burning capabilities. The Web site proclaims that there is no starvation with this diet, yet it does state that followers should limit calories to less than 800 per day.

Pros:  Grapefruit is a good source of beta-carotene, fiber, and vitamin C. The white pith contains pectin and bioflavonoids.

Cons:

• No scientific studies support the claim that grapefruit contains “fat-burning enzymes.”
• The diet does not supply adequate calories.
• It is a short-term, temporary approach to weight loss.

Conclusion: There are many fad diets out there, and their popularity knows no bounds. Fad dieting is often cyclical, causing weight fluctuation, slowed metabolism, and a negative relationship with food. In my practice, I encourage clients to eliminate food restrictions and embrace all types of foods. This can very difficult for a lifelong dieter to do, but worthwhile. Dieting is temporary, but the need to eat will never end. As a dietitian, one of my goals is to help people understand their unique dietary needs and work toward creating a positive relationship with food—and the scale.

References:

1. Every Diet. Diet Plans encyclopedia. Available at: Everydiet.org. Accessed on May 13, 2010.
2. Diets in Review. Available at: www.dietsinreview.com. Accessed on May 13, 2010.
3. Johnston et al. Vinegar Improves Insulin Sensitivity to a High-Carbohydrate Meal in Subjects With Insulin Resistance or Type 2 Diabetes. Diabetes Care. January 2004 vol. 27 no. 1 pp. 281-282.
4. WebMD: Better information. Better health. Available at: www.webmd.com/vitamins-supplements/ingredientmono-816&activeIngredientName=APPLE+CIDER+VINEGAR. Accessed on: May 13, 2010.
5. Grapefruit Diet Plan for Beginner. Available at: www.grapefruit-diet-plan.org. Accessed on May 13, 2010.
6. Frassetto, et al. Metabolic and physiologic improvements from consuming a Paleolithic, hunter-gatherer type diet: Health benefits of a Paleo diet. European Journal of Clinical Nutrition. 63, 947-955, August 2009.
7. O’Keefe, James H. & Cordain, Loren. Cardiovascular Disease Resulting From a Diet and Lifestyle at Odds With Our Paleolithic Genome: How to Become a 21st-Century Hunter-Gatherer. Mayo Clin Proc. 2004;79:101-108.
8. CrossFit. Available at: http://www.crossfit.com/cf-info/start-diet.html. Accessed on May 13, 2010.
9. Koebnick, et al. Long-term consumption of a raw food diet is associated with favorable serum LDL cholesterol and triglycerides but also with elevated plasma homocysteine and low serum HDL cholesterol in humans. J. Nutr. 135: 2371-2378, Oct. 2005.
10. Tribole & Resch. Intuitive Eating: A Revolutionary Program that Works. St. Martin’s Griffin, 2003.
11. Master Cleanse. What is the Master Cleanse? Available at: http://themastercleanse.org/. Accessed on May 13, 2010.