In general, the lifestyle changes recommended by Drs. Oz and Roizen in "YOU: On a Diet" are a solid way to melt away fat and set yourself on a path of healthy eating and physical fitness. There are some drawbacks to be aware of, however, as with any diet.
While some may see this as a benefit, others may find a diet that encourages a bit of menu monotony to be a red flag. "YOU: On a Diet" recommends starting each day with a healthy breakfast to kick-start the metabolism, and suggests finding a couple of items for breakfast and lunch that you can make a habit. For some people, this limitation works because it eliminates the overwhelming number of choices available. But it's important to be aware that nutritional monotony might increase the risk of developing nutritional deficiencies, depending upon what you limit yourself to for breakfast and lunch.
Be smart about how you put your plate together. Choose healthy fats including monounsaturated, polyunsaturated and omega-3 fatty acids like those found in avocados and olive oil; whole grain breads and cereals; fruits and vegetables for antioxidants; essential vitamins and minerals; and low-fat dairy. If you're eating well-balanced meals for breakfast and lunch, it's OK to repeat those same menu items day in and day out, but be sure those meals are nutritionally well-rounded.
Menu monotony may lead some people to stray from a diet. If you're eating oatmeal for breakfast every morning and steamed salmon every day for lunch, you may not look forward to the same old meal and may give in to cravings. But the five things that aren't allowed in this new lifestyle aren't meant to deprive anyone of good, tasty foods. Consider pancakes, for example. While run-of-the-mill buttermilk pancakes can't be part of this new lifestyle, something like oatmeal blueberry or whole wheat apple cranberry variations can. Be open to a variety of foods, and you may find you really don't miss the foods you used to rely on.