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What Makes The Best Diet?

June 21, 2019

Diet is an important factor when considering overall health. Television shows, books, and various media outlets are saturated with advice on what and how to eat. A lot of information is conflicting, which often makes it hard to choose the right diet. How can there be so many “best” diets?  Low carb proponents would have us believe low carb is the way to go. Proponents of a low-fat diet insist that’s the way to go if health and weight loss are your primary concerns. Those are two of the many diets on the market. Is there a single best diet?

Various eating strategies produce weight loss and improve health. Some key points from the research on different diets:

• Generally, obesity-related conditions are significantly improved with modest weight loss of 5–10 percent.

• Calorie balance is a major determinant of weight loss.

• Regardless of what’s eaten, diets that consistently reduce calorie intake (below maintenance) result in weight loss.

• Generally, free-living (unrestricted) overweight individuals who consume high-fat, low-carb diets consume less-than-maintenance level of calories.

• Overweight individuals consuming low-fat and very low-fat diets lose weight because they consume fewer calories than their maintenance level.

In the short-term, high-fat, low-carb ketogenic diets cause a greater loss of body water than body fat. In the long term, low-carb, reduced-calorie diets result in significant fat loss. Proteins are also lost if protein intake isn’t sufficient. There are numerous low-carb diets consisting of a range of protein levels. A properly planned, moderate-fat, balanced, nutrient reduction diet is nutritionally adequate and appears relatively easy to follow for most people.

Generally, as body weight decreases, so do blood insulin, leptin, blood pressure, and plasma triglyceride levels. Many factors influence appetite, hunger, and subsequent food intake, including macronutrient content, neurochemical factors, hormonal signals, gastric signals, hedonistic qualities of food, genetic, environmental, and emotional factors.

When considering dietary compliance (that is, sticking to a diet), it’s important to consider not just food intake but also physiological and psychological factors (group support, frequency of dietary counseling, and coping with emotional eating).

A standard ketogenic diet contains fewer than 100 carbohydrates per day, with protein and fat levels varying. Under normal conditions ketone bodies are present in the bloodstream in small amounts, approximately 0.1 mmol/dl. Ketosis is defined clinically as a ketone blood concentration above 0.2 mmol/dl. Low-carb diets are often low in vitamin E, vitamin A, thiamin, vitamin B6, folate, calcium, magnesium, iron, potassium, and dietary fiber, thus may result in a need for supplementation. Poorly planned vegetarian diets are often low in vitamin E, B12, zinc, calcium, essential fatty acids, essential amino acids, iron, and phosphorus, thus those dieters may need supplements as well. Low-fat, high-carb diets often lower LDL and HDL cholesterol. Generally, studies have found protein is more filling than carbohydrate or fat.

To learn more about different diets and their range of effects, I highly recommend reading the article Popular Diets: A Scientific Review, by Freedman and colleagues (2001). Some of the key points mentioned above were taken from that classic review paper. Throughout the paper the researchers highlight the importance of calories and their impact on different outcomes. People are often confused about the role of calories in diet, resulting in questions and articles addressing whether calories matter. There is extensive research showing the importance of calories regarding various outcomes (weight gain, weight loss, and health indicators). So, why is there so much confusion?

Much of the confusion regarding the importance of calories is due to the use of food heuristics, mental shortcuts about food (Hale 2010). Examples of food heuristics include adherence to low-carb diets, low-fat diets, traditional bodybuilder diets, and volumetric eating (emphasizing bulk and quantity of food). These examples often lead to calorie deficits without having to count calories. To be clear, just because one doesn’t count calories doesn’t mean they aren’t important. Not being conscious of the number of calories consumed is the norm. Diets and eating plans that result in weight loss are diets that create calorie deficits, and those that result in weight gain are those involving calorie surplus.

Dansinger and colleagues (2007) conducted a randomized trial comparing popular diets (Atkins, Ornish, Weight Watchers, and Zone) to assess adherence rates and the effectiveness of weight loss and cardiac risk factor reduction. The main outcome measures were changes in weight and cardiac risk factors and self-report measures of how well they stuck to the diet. The researchers concluded that each diet resulted in weight loss and a decrease in cardiac risk factors. Overall adherence rates were low, and sticking to the diet resulted in greater weight loss and greater reduction in cardiac risk factors.

When choosing the right diet consider the best diet for your specific goals, circumstances, and lifestyle. Factors to consider when choosing a diet include:

Looking Past the Hype

To optimize a diet’s effectiveness, consider factors including activity level, primary goals, metabolic abnormalities, past dieting experiences, responses to meal frequency, psychological issues, convenience issues, food availability, time availability, and support systems. Many weight management programs are too generic and wrongly suggest that one size fits all; for example, recommending the same calorie level for an active athlete and an inactive individual is problematic.

Recommendations Based on Science

Reliable scientific information is derived from the weight of the evidence. When journalists or advertisements claim that “science says,” proper referencing should be provided. Proper referencing does not refer to packaging or promotional information, testimonials (no matter who they are from), or ads that contain scientific-sounding explanations. It means reference to sources that reliably report on scientific research. Acquiring a basic understanding of research methodology and how to read research papers will allow you to be better equipped to evaluate nutrition claims. Beware of those that often use the phrase studies tell us but provide no references to such studies.

Weight Loss Is Not the Only Measurement of Success

Weight loss comes in various forms, including fat, body proteins, water, glucose, and vitamin storage. Body composition can be important for health, performance, and physique. In addition to weight loss, the feeling of well-being, body measurements, and a blood panel are important for some people when determining the success of a program and overall health. Don’t rely on the scale alone as a measure of success.

Beware of Programs that Claim ‘Special’ Food or Supplements Are Essential

Supplements can play a positive role in weight management and health but they’re not magic. Supplements may complement your program or make things more convenient, but insisting that specific supplements or food replacements must be consumed is incorrect. Special packaged foods and supplements are not necessities for weight loss.

Is There A Best Diet?

There is no “best diet” for everyone. If you can’t stick to the diet, it won’t be successful. The psychological aspects of dieting are often overlooked but are crucial for success. For many people whether they stick to a diet is determined largely by psychological issues mentioned earlier. Pick a diet that you can stick with. If you hate all of the foods included in the diet and you’re anxious about starting the diet, then choose a different one. A quality diet doesn’t have to consist of only bland foods. Liking what you eat is important to long-term adherence; it is also an important predictor of what you consume over the long term (Hale 2018). There are plenty of spices and other low-calorie, safe additives that can make your nutritious diet a tasty one.

Recommendations for a Quality Diet

• Consume adequate calories (whether you’re consciously counting calories or not).

• Consume essential nutrients (those that can’t be made in adequate amounts in the body).

• Account for individual likes and dislikes (the primary determinant of what people eat over a lifetime is food likes and dislikes; Eertmans et al. 2001).

• Account for metabolic abnormalities (e.g., diabetes, insulin resistance, and other factors).

• Take occasional breaks (you don’t have to stick to the program 100 percent of the time to see the benefits; breaks provide physiological and psychological benefits).

• Account for environmental factors (such as expectations, variety- and sensory-specific satisfaction, dining out or with others, and so on).


Dansinger, M., Gleason, J., and Griffith, J. 2005. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction. JAMA 29(1): 43–53.

Eertmans, A., Baeyens, F., and Van den Bergh, O. 2001. Food likes and their relative importance in human eating behavior: review and preliminary suggestions for health promotion. Health Education Research: Theory and Practice 16(4): 443–456.

Freedman, M., King, J., and Kennedy, E. 2001. Popular Diets: A Scientific Review. Obesity Research 9(1): 1–40.

Hale, J. 2010. Should I Eat The Yolk? Separating Facts from Myths To Get You Lean, Fit and Healthy.  Berkeley, CA: Ulysses Press.

———. 2018. What Influences Our Food Likes and Dislikes?. Psych Central. Retrieved on June 15, 2019, from