What qualifies as a good diet? It should include nutritious foods that provide all the necessary nutrients for normal health. It should do no harm to your general health. It must be a diet that one can tolerate and integrate into one’s lifestyle for the long term. The best diet should not produce unpleasant feelings or leave one feeling hungry all the time. Popular diets tend to be gimmicks and are a challenge to stick to. Many people stop their chosen diet, not because of their risk factors (which most are rarely aware of), but because they simply get tired of the effort to maintain the dietary regimen, or because they feel hungry all the time. If all one can think about is food, it’s hard to focus on the other priorities in life.
Some diets are both unwise and difficult to follow.
Lots of Fat: The most popular of these is the Keto Diet. Keto is a low-carb, high-fat diet that aims to put the body in a state of ketosis by elevating the level of ketones in the blood. Overall, this is a bad idea! Ketones are acids and, if ketosis is achieved, they would lower the blood pH to the point where you die. Fortunately, this diet is so badly conceived that true ketosis doesn’t occur. According to keto guidelines, you must consume 80% of your calories from fat, which, over time, becomes boring, unappetizing, and unsustainable. If you choose the Keto Diet, watch out for kidney stones, severe fatty liver, vitamin and nutrient deficiencies, and heart disease. There is also an increased risk of anxiety and depression, headaches, dizziness, fatigue due to low blood sugar, nausea, and constipation due to an imbalance in the gut microbiome. You could go old school and choose the Atkins Diet, which also emphasizes eating lots of fat and protein. You will lose weight, but your kidneys and liver will fight to overcome the increased nitrogen load and dehydration.
Lots of Protein: The Paleolithic diet is naively based on what we think early humans ate about two million years ago. You can eat a diet of all meats, fruits, vegetables, nuts, and roots, like the Paleolithic diet recommends, but no matter what you do, the meats, fruits, vegetables, nuts, and roots you eat will be twenty-first-century versions of meats, fruits, vegetables, nuts, and roots—not Paleolithic ones. Many of the foods from the Paleolithic period were species of wild plants and animals that no longer exist in any form today. Many of the wild animals our distant ancestors hunted are completely extinct. Also, it’s naïve to think that all Paleolithic people ate the same diet. In fact, during the Paleolithic period, people ate far less meat than the average person today. Obtaining meat was a very dangerous thing to do. The Paleo diet ranks poorly among diet experts, who view it as too restrictive and nutritionally inadequate to be healthy or sustainable. The elimination of whole grains may mean a decreased intake of fiber, which is beneficial to gut health. Also, the diet does not allow the consumption of legumes, which are highly beneficial to gut health and rich in magnesium, selenium, and manganese. None of these issues probably mattered to people living during the Paleolithic age, since the majority of them died before the age of 30 years.
Healthy Balanced Diets
For maintenance of good health, the DASH diet, the Antioxidant diet, which is essentially the Anti-inflammatory diet, and the more familiar Mediterranean diet are all excellent choices. These diets emphasize nutrient-dense, whole foods, including fruits, vegetables, whole grains, healthy fats, and lean proteins, while limiting the consumption of refined sugars, processed foods, and saturated fats: 40% to 50% of calories from healthy carbs, 30% from fat, 20% to 30% from protein.
However, for good health combined with weight loss (which is necessary, given that seventy-five percent of Americans are either overweight or obese), current evidence overwhelmingly indicates that caloric restriction is the only valid, scientifically proven dietary intervention [for more details, see my book Your Brain on Food] that can reduce body weight, slow the aging process, and improve mental health without forcing you to give up either proteins, fats, or carbohydrates. However, caloric restriction is not easy! Most people give up on this diet because they feel hungry all day long.
The answer lies in knowing when to eat.
The body is greatly influenced by our daily biorhythms. One recent study examined the effects of eating the majority of each day’s calories earlier or later in the day. Overweight women were divided into a breakfast group or a dinner group for 12 weeks. The breakfast group showed greater weight loss and waist circumference reduction. Fasting glucose and insulin decreased significantly in the breakfast group. Average triglyceride levels decreased by 33.6 percent in the breakfast group and increased significantly in the dinner group. Most importantly, the women who ate a big breakfast reported feeling satisfied by their food and being less hungry for the rest of the day! This is a diet that people can stick with for the long term.
Overall, be an omnivore with a balance of all nutrients like the Mediterranean Diet. However, given the role of circadian rhythms in how we metabolize calories, the current data suggest that we eat a really big breakfast and a small dinner. I suggest the new mantra: Eat breakfast like a king, lunch like a prince, and dinner like a pauper.