If you are confused about what is or is not a healthy diet, don’t despair. You’re not alone. Nutritional scientists are confused as well.
As Science magazine stated in a recent issue:
“Advice on what constitutes a healthy diet is more prevalent and more inconsistent than ever.”
Why is there so much confusion about healthy diets?
There are many reasons for this state of affairs.
Nutrition is complicated
In addition to the 3 main macronutrients (carbohydrates, fats, proteins), there are hundreds of micronutrients. These are compounds, such as vitamins and minerals, that are present in the diet in minute amounts. We also know that many of dietary components interact with each other. this adds enormously to the complexity.
We’re not only feeding ourselves
When we eat we are feeding not only ourselves but trillions of bacteria that reside in our gut. Our diet, as well as our physiological and health status, determine which bacterial populations inhabit and thrive in our gut. This, in turn, determines much of our own health.
It’s not only what but also when you eat that matters
When we think about diet, we naturally concentrate on what we eat. However, recent advances in chronobiology, the science of biology in the context of time, tell us that when we eat can make a difference as well.
We are all different
Our genetic makeups, our physiologies, our hormonal status, even our anatomy, all make us unique. Is it any wonder that one size doesn’t fit all when it comes to a healthy diet?
Underfunding the science of nutrition
Last but not least, we are underfunding nutrition science. Despite the complexity and enormous health and economic costs of obesity, the U.S. invests a fraction of a cent on nutrition research for each dollar spent on treatment of diet-related chronic disease. Consequently, nutritional studies are small, statistically underpowered, and all too often poorly designed.
It shouldn’t be a surprise then, that these factors have combined to make us susceptible to the myriad of profit-seeking charlatans pushing dietary fads in books and on social media, radio, and TV.
Bringing clarity to the issue
A recent issue of Science magazine tried, in a series of articles to bring some clarity to the issue. If one could distill the root cause of the public confusion about diet into one issue, I would think it would be the role of fat in the diet.
An article in the same issue of Science titled “Dietary fat: From Foe to Friend?” is authored by experts with divergent opinions on the subject. Some of them advocate a low-fat, high-carbohydrate diet. Others advocate a low-carbohydrate, high-fat diet.
Amazingly, during this age of shouting rather than listening, there were many areas of agreement. This, I think, will bring much-needed clarity to the subject. So, let me reiterate a few of the main consensus points:
The main consensus points
“1. Good health and low chronic disease risk can be achieved for many people on diets with a broad range of carbohydrate-to-fat ratios as long as the focus is on nutrient quality.
2. The general population will benefit from the replacement of saturated fats with naturally occurring unsaturated fats.
3. Industrially-produced trans fats are harmful and should be eliminated.
4. An issue that requires more study is that the metabolism of saturated fat may differ on carbohydrate-restricted diets.
5. Health benefits accrue when highly processed carbohydrates (including refined grains, potato products, and free sugars) are replaced with unprocessed carbohydrates (nonstarchy vegetables, whole fruits, legumes, and whole or minimally processed grains).
6. Biological factors appear to influence responses to diets of differing macronutrient composition. People with relatively normal insulin sensitivity and β cell function may do well on diets with a wide range of carbohydrate-to-fat ratios. Those with insulin resistance, hypersecretion of insulin, or glucose intolerance may benefit from a lower-carbohydrate, higher-fat diet.
7. A ketogenic diet may confer particular metabolic benefits for some people with abnormal carbohydrate metabolism. But this possibility requires long-term study.
8. Well-formulated low-carbohydrate, high-fat diets do not require high intakes of protein or animal products. Reduced carbohydrate consumption can be achieved by substituting grains, starchy vegetables, and sugars with nonhydrogenated plant oils, nuts, seeds, avocado, and other high-fat plant foods.”
The authors conclude that “there is a broad agreement regarding the fundamental components of a healthful diet that can serve to inform policy, clinical management, and individual dietary choice. Nonetheless, important questions relevant to the epidemics of diet-related chronic disease remain. Greater investment in nutrition research should assume a high priority.”
Three practical points
Three practical points stand out:
1. Most people should benefit from a low-fat high carbohydrate diet.
2. Some people who suffer from metabolic abnormalities, such as diabetes and pre-diabetes, may benefit from a ketogenic diet. But remember, the scientific jury is still out on this one. As cautious scientist is wont to say, more research and vastly more funding are needed.
3. Aim for nutritional quality above all. Whichever diet strikes your fancy, keep the quality of the nutrients high. Even if you insist on the wonders of a ketogenic diet, the fat in Kentucky Fried Chicken won’t do. Even if you opt for a high-carbohydrate low-fat diet beware of high-sugar drinks.
What would Grandma say?
The points of consensus rest on a detailed recitation of the metabolic and epidemiological studies. The more scientifically curious among should definitely delve into this literature.
But when all is said and done, I end up with the feeling of best summarized with this statement: “Tell me something I didn’t know.”
Our grandmothers could have and probably did, tell us all of this. Their generation didn’t have to worry about industrially-processed food -there was none.
They didn’t have an obesity problem because they were too poor to go to restaurants and gorge themselves with enormous portions of high-fat fast food.
So, what is my take?
If you ask me what is the ideal diet, I always come back to the tried-and-true: the Mediterranean diet.
It emphasizes the consumption of a variety of high-quality foods:
- unsaturated fats (olive oil),
- fish, and
- limited red meat consumption.
You notice that the emphasis is on variety.
It does not exclude a particular food group or confine you to specific macronutrient ratios. This is not based on the fevered imagination of some diet huckster.
So the evidence is already in, and although the scientific jury is still deliberating on the plusses and minuses of specific nutrients and the ratios between them, this only leads to analysis paralysis.
Life is too short to wait for the definitive, final, final verdict, if it may ever come.
The bottom line:
Just eat well and enjoy life.
Related Content: The Benefits of Fasting – with Food!
Dov Michaeli, MD, PhD
Dov Michaeli, M.D., Ph.D. (now retired) was a professor and basic science researcher at the University of California San Francisco. In addition to his clinical and research responsibilities, he also taught biochemistry to first-year medical students for many years.
During this time he was also the Editor of Lange Medical Publications, a company that developed and produced medical texts that were widely used by health professionals around the world.
He loves to write about the brain and human behavior as well as translate knowledge and complicated basic science concepts into entertainment for the rest of us.
He eventually left academia to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early-stage biotech company that developed products to improve post-surgical pain control.
Now that he is retired, he enjoys working out for two hours every day. He also follows the stock market, travels the world, and, of course, writes for TDWI.