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Low Fat Diets for Weight Loss

Low fat diets have long been considered an effective strategy for weight loss. They promote a healthy balance of macronutrients, whole foods, and dietary fiber while reducing calorie intake. In this article, we will discuss the benefits of low fat diets for weight loss and explore human population studies that support this approach.

Benefits of Low Fat Diets for Weight Loss

  1. Macronutrient Calorie Density: Low fat diets focus on reducing calorie-dense foods, particularly those high in fat. As fat has more than double the calories per gram compared to carbohydrates and proteins, reducing fat intake can significantly lower overall calorie consumption.

  2. Whole Food Calorie Density: Low fat diets encourage the consumption of whole foods, which typically have lower calorie density. Fruits and vegetables, in particular, have very low calorie densities, allowing you to eat more volume while consuming fewer calories.

  3. Fiber Content: Low fat diets promote the consumption of fiber-rich foods, such as fruits, vegetables, and whole grains. Fiber has been shown to play a vital role in weight loss by promoting gastric distension, which contributes to a feeling of fullness and satiety.

  4. Gut Health and Gut Bacteria: Fiber also plays an essential role in maintaining gut health and promoting a healthy balance of gut bacteria. A healthy gut microbiome has been linked to improved weight loss outcomes and overall health.

  5. Thermic Effect of Food: Low fat diets can increase the thermic effect of food, or the energy required to digest and process nutrients. This increase in energy expenditure can contribute to weight loss over time.

Population Studies and Historical Diets

Traditional human diets since the agricultural revolution have predominantly consisted of high carbohydrate, low fat foods, contrary to popular "paleo" or low-carbohydrate beliefs. Even our Paleolithic ancestors likely consumed a higher carbohydrate diet, given the difficulties in procuring meat and the availability of wild grains and fruits.

Contemporary population data supports the notion that high carbohydrate, low fat diets are common across the globe. In Asia, Africa, and South Asia, diets are primarily plant-based and high in carbohydrates. Indigenous populations worldwide also follow similar dietary patterns.

Relevant research includes:

  • Eaton SB, Eaton SB 3rd, Konner MJ. Paleolithic nutrition revisited: a twelve-year retrospective on its nature and implications. Eur J Clin Nutr. 1997 Apr;51(4):207-16.

  • Popkin BM. Global nutrition dynamics: the world is shifting rapidly toward a diet linked with noncommunicable diseases. Am J Clin Nutr. 2006 Aug;84(2):289-98.

The Low Carbohydrate Craze: A Fad or a Sustainable Solution?

The current American low carbohydrate craze is a dietary fad that has gained popularity without strong scientific support. This trend has been criticized for promoting inflammation and failing to provide sustainable, long-term weight loss results.

In conclusion, low fat diets that emphasize whole foods, high fiber, and low calorie densities have a strong foundation in both historical and contemporary population data. These diets can promote weight loss through various mechanisms, including reduced calorie intake, increased satiety, and improved gut health. In contrast, low carbohydrate diets have been shown to be a fad, often causing more harm than good. By focusing on a low fat, plant-based diet, individuals can achieve sustainable weight loss and improve their overall health.

More Support for Low Fat Diets for Weight Loss

Low-fat diets have been a popular weight loss strategy for several decades, with numerous medical studies and research supporting their efficacy. The primary idea behind low-fat diets is that they reduce the overall caloric intake by limiting the amount of fat consumed, since fat has more than twice the calories per gram compared to carbohydrates and proteins. The following is an overview of the medical literature that supports low-fat diets for weight loss.

  1. The National Institutes of Health (NIH) sponsored the Women's Health Initiative (WHI), a long-term national health study that aimed to address the most common causes of death, disability, and impaired quality of life in postmenopausal women. One arm of this study, the Dietary Modification Trial, enrolled 48,835 postmenopausal women and followed them for an average of 8.1 years. Participants in the low-fat diet group were encouraged to reduce their total fat intake to 20% of daily calories while increasing their consumption of fruits, vegetables, and grains. The study found that the low-fat diet group experienced a modest but significant reduction in body weight, compared to the control group (Howard et al., 2006).

  2. The Look AHEAD (Action for Health in Diabetes) study aimed to assess the impact of an intensive lifestyle intervention, including a low-fat diet, on cardiovascular outcomes in overweight and obese individuals with type 2 diabetes. Participants in the intervention group received ongoing support to achieve and maintain a low-fat diet, along with physical activity goals. The study demonstrated that the intensive lifestyle intervention group experienced significant weight loss compared to the control group, with an average weight loss of 8.6% of initial body weight at one year (Wadden et al., 2011).

  3. The PREDIMED (Prevención con Dieta Mediterránea) study investigated the effects of a Mediterranean diet supplemented with extra-virgin olive oil or nuts compared to a low-fat diet in the primary prevention of cardiovascular disease. Although the primary focus of the study was cardiovascular outcomes, weight loss was also evaluated. The study found that participants in the low-fat diet group experienced a modest but significant weight loss compared to the Mediterranean diet groups (Estruch et al., 2013).

  4. A meta-analysis of randomized controlled trials by Tobias et al. (2015) compared low-fat diets to other diets, such as low-carbohydrate, Mediterranean, and high-protein diets, in terms of their efficacy for weight loss. The analysis included 53 studies with a total of 68,128 participants. The study found that low-fat diets led to significant weight loss but were not as effective as low-carbohydrate diets in the short term. However, the difference in weight loss between the diet types was small and not considered clinically significant.

  5. Another meta-analysis by Hooper et al. (2012) examined the impact of reducing or modifying dietary fat intake on body weight and cardiovascular risk factors. This analysis included 33 randomized controlled trials with a total of 73,589 participants. The results demonstrated that reducing dietary fat intake led to a small but significant reduction in body weight, body mass index (BMI), and waist circumference.

It is important to note that while low-fat diets have been shown to be effective for weight loss, they are not universally successful for all individuals. Some recent studies and meta-analyses have suggested that low-carbohydrate diets may be more effective for weight loss, at least in the short term, for certain populations (Hall et al., 2015; Mansoor et al., 2016). However, long-term adherence to low-carbohydrate diets can be challenging for some individuals, and the long-term health effects of these diets remain uncertain.

In the broader context of weight loss, it is essential to consider individual preferences, dietary adherence, and sustainability when choosing a weight loss plan. There is no one-size-fits-all approach, and different diets may be more effective for different people based on their individual needs and preferences.

In conclusion, the medical literature supports low-fat diets as an effective weight loss strategy for some individuals, particularly when combined with other lifestyle modifications such as increased physical activity and portion control. However, it is essential to consider other factors, such as individual preferences, dietary adherence, and long-term sustainability when choosing a weight loss plan.


  1. Howard, B. V., Manson, J. E., Stefanick, M. L., Beresford, S. A., Frank, G., Jones, B., ... & Prentice, R. (2006). Low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial. JAMA, 295(1), 39-49.

  2. Wadden, T. A., West, D. S., Delahanty, L., Jakicic, J., Rejeski, J., Williamson, D., ... & Look AHEAD Research Group. (2011). The Look AHEAD study: a description of the lifestyle intervention and the evidence supporting it. Obesity, 14(5), 737-752.

  3. Estruch, R., Ros, E., Salas-Salvadó, J., Covas, M. I., Corella, D., Arós, F., ... & PREDIMED Study Investigators. (2013). Primary prevention of cardiovascular disease with a Mediterranean diet. New England Journal of Medicine, 368(14), 1279-1290.

  4. Tobias, D. K., Chen, M., Manson, J. E., Ludwig, D. S., Willett, W., & Hu, F. B. (2015). Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis. The Lancet Diabetes & Endocrinology, 3(12), 968-979.

  5. Hooper, L., Abdelhamid, A., Moore, H. J., Douthwaite, W., Skeaff, C. M., & Summerbell, C. D. (2012). Effect of reducing total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies. BMJ, 345, e7666.

  6. Hall, K. D., Bemis, T., Brychta, R., Chen, K. Y., Courville, A., Crayner, E. J., ... & Chung, S. T. (2015). Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity. Cell Metabolism, 22(3), 427-436.

  7. Mansoor, N., Vinknes, K. J., Veierød, M. B., & Retterstøl, K. (2016). Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 115(3), 466-479.

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