Does “The Healthiest Diet” Really Exist?

Reviewed by Dr. Jonathan Bonnet, MD, MPH, Judy Singer, RD and Heather Hodson, RD

The United States (U.S.) is one of the wealthiest nations in the world, but research shows that we are far from the healthiest. When compared with other high-income countries, American lifespan and quality of life lags behind. We live shorter lives and experience more injuries and illnesses. And according to a study examining the state of U.S. health between the years 1990 and 2016, diet is one of the leading causes of death and disability-adjusted life-years (a combination of years of life lost due to premature death and time lived in states of less than full health).

There are many factors that impact what we eat. Economic stability, education, healthcare, neighborhood, and social and community contexts may be some of the most significant barriers when it comes to access to foods that support healthy diets.

But data suggests that even the most advantaged Americans may be in worse health than their counterparts in other nations. Which leaves many of us wondering, is there one diet that’s best for our health? And if so, what is it?

What is a diet?

In popular Western culture, the term “diet” has become synonymous with a restrictive eating pattern designed with the primary goal of losing weight. In fact, weight loss as an industry has become so pervasive in the U.S. that it reached a peak valuation of $78 billion in 2019, according to Marketdata Enterprises.

But the word “diet” can also be used to describe a person or community’s general eating or dietary pattern. For example, there are several general differences between a Japanese diet and a West African diet. People in Japan are more likely to eat larger quantities of fish, soybean, and green tea, while those in West Africa are more likely to eat diets rich in cassava, yams, and taro.

There are also numerous ways to measure “health” in the context of a healthful diet. While often thought of in terms of calories or vitamins, intentional food choices offer a number of health benefits that promote wellbeing and longevity.

What are the different kinds of diets?

In reality, the total number of diets and dietary patterns is immeasurable. With so many potential variations, there is no single existing inventory detailing all of the major and minor subtypes of diets.

However, when looking at some of the most popular diets and dietary patterns in the U.S., there are several categories that emerge:

  • Low-carbohydrate diets: There is no universally accepted definition for low-carbohydrate diets, though they are generally characterized as diets where carbohydrate intake is 45% or less of total calorie intake. Examples include the South Beach diet, Atkins diet, and ketogenic diet. The carbohydrate content can vary, with ketogenic diets being on the lowest end, generally allowing 20-50 grams of net carbohydrates per day. The popularity of low-carbohydrate diets has surged in recent years, due in part to its effectiveness in short-term and moderate-term weight loss, as well as improvements in cardiovascular and metabolic markers. Importantly, many of the potential benefits and risks can be attributable to the quality of the fats that are included and lack of quality in the carbohydrates being excluded. However, there is no clear evidence that a low-carbohydrate diet is more healthful than alternatives in the long-term.

  • Low-fat diets: These diets focus on the restriction of total fat intake, generally consisting of 20% or less of total calorie intake. When consisting mostly of plant-based foods, low-fat diets have been shown to prevent recurrent myocardial infarction in adults with high risk. A very low-fat diet may also support regression of coronary atherosclerosis. However, for patients without specific cardiovascular risks, diets with monounsaturated fats and polyunsaturated fats may reduce risk for stroke and heart disease, lower blood pressure and inflammation, and reduce blood pressure. (For a guide on which types of fats are in foods, see this helpful article here.) Therefore, it is important to talk to your healthcare provider about recommendations for eating fats in your diet based on your personal health status and goals.

  • Vegetarian diets: There are some instances in which vegetarian and low-fat diets overlap, but vegetarian diets can also be high in fats from sources like dairy (lacto vegetarians), eggs (ovo vegetarians), nuts, and cooking oils. Vegetarian diets generally don’t include animal meats like chicken, beef, or fish, although there are some versions that include chicken (pollotarian) or fish (pescatarian). However, just because the diet doesn’t include animal meat doesn’t necessarily mean that it will be inherently healthy. As with all dietary patterns that restrict specific items, it is important to be mindful when choosing the foods to “fill the nutritional gap.” Given the nature of the modern food supply, it may feel easy to reach for large quantities of cereals and ultra-processed foods, which have added ingredients such as sugar, salt, fat, and artificial colors or preservatives. Importantly, overly restrictive vegetarian diets (including vegan diets) can be associated with malnutrition and adverse health events.

  • Vegan diets: Vegan diets exclude all forms of animal products, including meat, fish, eggs, dairy, and honey. People who follow vegan diets may do so for presumed health benefits and/or ethical and environmental considerations. When well constructed to include necessary vitamins and minerals, vegan diets can be associated with health benefits including reduced inflammation, reduced risk of cardiovascular disease and cancer, and improved insulin sensitivity. However, it is important to note that vegan diets can also be associated with deficiencies in nutrients that are commonly found in animal-derived foods, including vitamin B12, iron, and vitamin D. Being intentional about adding plant-based sources of these nutrients can help to prevent this. Additionally, eating only plant foods doesn’t guarantee a healthy, balanced diet. Oreos, Swedish fish, and sugar are vegan, so don’t let plant-based labeling fool you! High sugar and ultra-processed food intake (foods that are typically high in calories, salt, sugar, fat, artificial colors, flavors, preservatives, or stabilizers) will not promote health, even if they are considered vegan friendly. Like with vegetarian choices, it is important to prioritize which foods you select, even if considered vegan.

  • Low-glycemic diets: People with diabetes and pre-diabetes may be particularly drawn to low-glycemic diets, or diets that restrict the intake of foods with a high-glycemic index and/or glycemic load. These diets may exclude certain vegetables, most fruits, and other ultra-processed foods that contain refined and added sugar and starches. Studies show that low-glycemic diets and diets with a reduced glycemic load can support weight loss, insulin metabolism, diabetes control, inflammation, and vascular function in overweight and obese young adults.One of the reasons this eating pattern can support health is that a diet low in glycemic load typically limits or does not include ultra-processed foods that are high in refined starches and sugars. This will certainly improve diet quality. However, fat and protein in isolation have minimal effects on blood sugar. It is still necessary to pay attention to the types and quality of fat or protein that is consumed.

  • Mediterranean diets: Mediterranean diets follow the dietary patterns of Mediterranean countries. Chiefly, these diets focus on the consumption of olive oil, vegetables, fruits, nuts and seeds, beans and legumes, whole grains, wine, and fish. They include limited consumption of dairy and meat. Research shows that this diet is associated with increased longevity, preserved cognition, and reduced risk of cardiovascular disease.

  • Paleolithic diets: Paleolithic diets, also called Paleo diets, are restriction-based diets that exclude dairy, grains, and ultra-processed foods that would have been unavailable during the Stone Age. Instead, Paleo diets focus on the consumption of vegetables, fruits, nuts and seeds, eggs, and lean meats. Though in principle the diet prioritizes nutritious foods that are high in dietary fiber, most of the plant foods and nearly all of the animal foods available during the Stone Age are now extinct. When loosely interpreted as a dietary pattern based mostly on meat, there is little evidence on its health benefits. But when interpreted as a diet that’s primarily plant-based, there is evidence that it may offer more benefits than the Standard American Diet (SAD) in measures of body composition and metabolic health.

  • Mixed, balanced diets: The term “mixed, balanced diet” can be used to refer to diets that emphasize a variety of foods, which can include both plant-based and animal foods. They generally conform to dietary guidelines like those established by the Institute of Health. Two examples of this type of diet include the Dietary Approaches to Stop Hypertension (DASH) diet and the dietary pattern used in the Diabetes Prevention Program (DPP). However, more research on the long-term effects of these diets in direct comparison with others is needed to determine their effects on a population level.

  • Standard American Diet (SAD): The Standard American Diet (SAD) or traditional Western diet, is most associated with adverse health events and is high in ultra-processed foods, foods high in refined starches or sugars, and large consumption of processed or red meat. The SAD has been associated with significant negative health effects, including cardiovascular disease.

With any of these diets, there are potential limitations and less healthy ways to implement them.

Regardless of which dietary pattern you follow, experts urge individuals to consider the most healthful dietary principles when selecting a dietary pattern rather than diets that place an exaggerated emphasis on one nutrient, food, or type of restriction.

Why does my diet matter?

Scientific literature suggests that dietary factors are now the number one cause of deaths, surpassing tobacco use. While different analyses may conclude that tobacco use or physical activity could contribute more, the point is that diet plays a critical role in health and longevity.

Which diet is “best”?

Research largely suggests that no single diet defined by a specific set of rigid principles has been proven to be more healthful than another. However, there are some general dietary patterns that may be especially beneficial for your health. These patterns include:

  • A diet rich in plants

  • A diet containing minimally processed foods

  • A diet in which animal foods are products of pure plant foods (i.e., animals that have been fed a healthy, plant-based diet)

  • A diet that is personalized to your health needs or risks, lifestyle behaviors, and cultural or individual preferences

Michael Pollan coined the seven-word version of this as “eat food, not too much, mostly plants.” Additional recommendations may include eating a range of colors with each meal—with a particular emphasis on diversity of color in fruits and vegetables on the plate—to ensure that a variety of nutrients are consumed.

While this serves as an overarching set of guiding principles, we believe that with the right information, guidance, and self-awareness, all individuals are capable of finding the best dietary pattern for their unique needs. However, it can take time and some trial and error to figure out what works best for you. New research is helping to identify potential genes to help guide the process, though it is still preliminary and not very reliable, yet. Paying close attention to the impact that food has on your mood, energy levels, and lab values can help determine what eating pattern is best for your lifestyle.

How are diet and weight linked?

The foods we eat have far reaching effects on our health. Food selection and dietary patterns matter well-beyond the calories they provide and how they impact our weight.

In fact, research suggests against dieting for sustainable weight loss and instead focusing on long term changes that prioritize nutritive value. Generally, there is little evidence that diets alone (particularly restrictive diets) lead to lasting weight loss. Data also suggests that yo-yo dieting, short-term, and extreme weight loss can damage one's health and increase the risk of serious health issues, like heart disease.

Moreover, weight can be a tricky and sometimes unreliable assessment of health. Metrics like the Body Mass Index (BMI) don’t account for fat distribution, muscle mass, or body composition, so someone with a high BMI (like Dwayne Johnson, or “The Rock”) could be perfectly healthy.

Specifically, subcutaneous fat poses less of a health risk than visceral fat, but we can’t assess this from the scale alone. Having excess visceral fat—the fat that wraps around your internal organs—can put you at risk for a myriad of health consequences, including cardiovascular disease, dementia, and several types of cancer. But measuring visceral fat precisely will often require more technical equipment, including a DEXA scan, CT scan, or MRIs. In most people, 90% of body fat is subcutaneous.

Although thinner bodies are often believed to be healthier bodies, research points to a more nuanced relationship between weight and health. At the end of the day, weight is just one measurement of many that can determine one’s overall health status.

What if I’m interested in losing weight?

Many “diets” that offer quick fixes can work in the short-term, but will often rebound as soon as they are stopped.

If you are interested in losing weight and keeping it off, we recommend working with a dietitian and/or medical provider, who can help you identify strategies that are sustainable and well-suited for your lifestyle.

What are the benefits of changing my diet?

There are many potential benefits of making healthful changes to your diet. Some key measures of dietary pattern-driven health include:

  • Reducing risk for chronic disease (i.e. improving blood sugar, cholesterol, blood pressure, nutrient inadequacy, weight management, etc.)

  • Reducing the risk of mortality (i.e. heart disease, cancer, all-cause)

  • Enriched vitamin and mineral levels in the blood

  • Providing important nutrients for all the physiological processes in the body

  • Impact on gut microbiome

  • Reduction of inflammation

  • Impact on hunger and satiety signals

  • Promotion of stable energy, positive mood, and general well-being, whether through brain function and emotional regulation or being culturally relevant and individually palatable

Health supporting food choices can benefit your body and health long-term, but having a good relationship with food is equally important. Virtually everyone has opportunities to “improve” their diet in some way, but this should be viewed as a perpetual process, since most of us need to adjust our dietary patterns and nutritional needs throughout life.

How do I know which diet is right for me?

Finding a diet that’s right for you is a highly personalized mission. In addition to incorporating the general patterns listed above that encourage healthful eating, the right diet for you should be:

  • One that supports your health without a rigid or unsustainable set of rules

  • One that reflects your culture, beliefs, and lifestyle

  • One that is sustainable for your unique life and manageable in the long-term

Healthy diets come in a diverse range of possibilities. For example, someone who keeps Kosher and someone with a Caribbean background are likely to follow very different diets, but both diets can be healthy and a respectful reflection of that person’s culture, lifestyle, and beliefs.

Eating is an essential part of life, and it is one that can be both health-supporting and joyful. Our goal is to help you understand your eating patterns and include more behaviors that make you feel and function at your best. If you’re looking to optimize your diet but are unsure where to start, Forfend can help. Our whole person exams can help you optimize your approach to whole body wellness.


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