One surprising finding, Dr. Hazen said, was how a long-term diet that includes meat affected the amount of TMAO-producing bacteria in the gut and thus magnified the risk.

WSJ: New Health Culprit Carnitine Found in Red Meat

Over the long term, a diet with too much protein can pose risks of problems including kidney stones.

WSJ: Krave, Perky Jerky and Others Remake Beef Jerky as a Healthy Protein Snack

If your symptoms resolve after one month on a gluten free diet, and the diet does not stop working several months later, this is probably the case and you should do your best to follow a gluten free diet long-term.

CNN: Are there degrees of gluten sensitivity?

Dr Jebb and others expressed concern that, like any extreme diet, Atkins could pose long-term health risks.

ECONOMIST: Dieting

Finally, the diet can be expensive (grass-fed, organic meats and eggs are more expensive) and inconvenient due to the limitation of food choices, both of which make this diet less practical for the average person long term.

CNN: Is the Paleo diet healthy?

Not a vague, wishy-washy notion that I should "get in shape, " maybe "eat better" or possibly "go on a diet, " but rather a specific long-term plan to enhance my wellness in a way that would not only stick, but fit within the parameters of my busy life as a full-time lawyer, husband and father of four small children.

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But Meijer says the average diet lasts just days, and a company that favors health over taste risks market share in the long term.

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