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Fad Diets: Fact or Foe?

Mila Bjelica

posted: January 9th, 2019

With the new year come new resolutions, or in some cases revised resolutions with a revived sense of motivation. Weight loss and dieting are among the most common resolutions in North America. Throughout January, major news sources and lifestyles guides will be reporting the newest diet trends of 2019: the most effective diet to shed those extra pounds. Just as fast as these new trends come out, they are picked up by individuals who choose to diligently follow these recommendations to cut out carbohydrates, count food on a points system or limit fats completely. Each diet is marketed as the miracle solution to weight loss, and credits its proprietary macronutrient distribution for this effect. What more, there is intense debate over what diet is truly the most effective and what combinations of food will lead to achieving those weight loss goals. However, is there true scientific evidence to suggest that these diets are really effective? When we consider how our metabolisms work, is there truly reason to choose one diet over another?


Numerous studies comparing various types of diets have been conducted, only to find confounding evidence on which diets are most effective for weight loss. However, the most convincing evidence comes from a large randomized control trial which assessed the effects of different macronutrient compositions in diets on weight loss.


The study by Sacks et al., compared diets containing different macronutrient compositions: fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. Interestingly, all successful participants lost an average of 6% if their initial body weight within the first 6 months, regardless of the diet assignment. Overall it was found that all four diets had a similar effect on weight loss and maintenance over the span of 2 years. Even factors such as satiety adherence, hunger and satisfaction were evenly matched across all dietary groups. In fact, it appeared that adherence to the diet was a strongly associated to weight loss. This suggests that any diet that controls caloric intake can actually be effective in reducing weight, provided the dieter is consistent.


Given this, what should actually be considered when choosing a diet to follow? It is important to note that many fad diets can actually be harmful to one’s health because they do not consider nutritional quality or adequacy (Freedman, 2001). In fact, consuming food from all macronutrient groups facilitates a more nutritionally adequate diet. For instance, carbohydrate-free diets such as the ketogenic diets are deficient in vitamins and minerals such as vitamin E, A, B6, magnesium, iron, potassium, calcium, and dietary fibre, all necessary for optimal health (Freedman, 2001). Additionally, they can also be high in saturated fats and cholesterol (Freedman, 2001). Even in weight loss, health is always most important therefore consulting a physician or nutritionist is always a good idea.


One golden rule to weight loss still remains: caloric balance is a major influencer of weight loss- regardless of caloric source. Reduce caloric intake and increase caloric output (physical activity).




Sacks, F. M., Bray, G. A., Carey, V. J., Smith, S. R., Ryan, D. H., Anton, S. D., ... & Leboff, M. S. (2009). Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. New England Journal of Medicine, 360(9), 859-873.


Freedman, M. R., King, J., & Kennedy, E. (2001). Popular diets: a scientific review.