Lifting the Lid on Fad Diets: The Paleo Diet

Lifting the Lid on Fad Diets: The Paleo Diet

The Paleo diet took over the health scene back in 2012. Instead of taking on modern science the diet recommended stripping the modern diet back to day dot. Does eating like a caveman appeal to you?

What is a Fad diet?

A fad diet is a diet that promises weight loss, body detoxification and/or improved health through what is usually a highly restrictive, unhealthy and unbalanced diet. Most fad diets are advertised as short-term regimes that cure physiological problems. Fad diets aimed at weight loss tend to provide fast results, due to the limited amounts of foods you can consume. However, the results are not sustainable in the long-term and the highly restrictive nature of these diets for significant lengths are associated with nutrient deficiencies, eating disorders and metabolic complications. More conventional, less restrictive forms of dieting can achieve the same fat loss results over longer periods, without severely depriving yourself of essential nutrients.

What is the Paleo diet?

The Paleo diet revolves around replicating the eating behaviours of our prehistoric ancestors. Advocates of Palaeolithic methodologies claim eating like a hunter-gatherer is still the most superior diet to avoid disease, increase longevity and improve body composition. Arguments for a Palaeolithic diet derived initially, not from modern science, but from the universal relevance of adaptation.

As the diet tries to mimic that of cavemen, it mainly focuses on the consumption of large quantities of meat (usually grass-fed and unprocessed) and fish, alongside a portion of vegetables. Small quantities of fruit, nuts, seeds and oils can be included. Grains, legumes, potatoes, dairy, processed foods and alcohol are to be avoided [1].

Unlike many fad diets that are targeted towards short-term weight loss results, the Paleo diet is advertised as a lifetime endeavour. The diet does not have strict limitations on meal frequency or caloric intake, and places nearly all its emphasis on ensuring Paleo users do not convert back to eating foods on their “banned list”. Brief instructions such as “restrict or avoid consumption of fruit, nuts and oils” are mentioned for those primarily looking to lose weight, but no specifications on nutrient requirements are advised.

Based on the list of foods you can eat, Paleo followers tend to consume a high protein, high fat, high saturated fat, high cholesterol, low carbohydrate diet.

Are Paleo claims backed by science?

We are not designed to eat grains or starch-based foods” – Paleo advocates fail to realise that starch-based foods were a staple of our prehistoric ancestors. Carbohydrate consumption, especially in the form of starch (plant root tubers, potatoes), has shown to have contributed significantly towards the acceleration of brain growth over the last 3 million years [2]. Evidence also conveys the genes that code for the enzymes needed to digest starch evolved about 1 million years ago, in the midst of the Palaeolithic era [3]. A true Paleo diet would include starch-based foods, not avoid them.

Avoiding carbohydrates improves health and body composition” – There is evidence for this claim when Paleo diets are compared to a Standard American Diet or Western Diet [4]. However, these diets should not be a baseline in which to compare when discussing healthy eating plans. Unsurprisingly, any restrictive eating plan will be superior for health and body composition when compared to a diet that currently contributes to the 37.9% adult obesity rate. When compared to other restrictive diets, such as a low-fat, no/low carbohydrate diets do not show improved health markers or faster weight loss [5][6].

Humans are intolerant to grains” – The recurring claim that gluten in grains causes intestinal issues in humans is highly exaggerated. Current estimates of gluten allergy prevalence are below 1% of the population, with gluten intolerance or non-celiac gluten sensitivity prevalence estimated at 0.5% [7]. To assume grains negatively impact on health when only a very small minority of humans notice digestive issues raises suspicion of Paleo’s legitimacy. To make it worse, half of the “major food allergens” designated by the Food Allergen Labelling and Consumer Protection Act are Paleo-approved.

Almost all legumes produce detrimental effects in our bodies... and are toxic” - The scientific literature (in both observational and controlled studies) on the health benefits of legume consumption is substantial. Legumes are fundamental components of some of the healthiest populations in the world. Beans, including fava, black, soy, and lentils, are the cornerstone of most centenarian diets [8]. The toxicity claims, centred around lectin content in beans, are also false as the heat during cooking completely denatures lectins. Cooked legumes are not only completely safe but their residual lectin levels fight cancer and various types of infection [9].

Does Paleo have benefits?

Looking past the collection of incorrect claims Paleo has, it does have its positives. The movements push to refrain from eating processed food and refined sugars is definitely a message that can never be said enough. 2016 survey notes ultra-processed foods could be comprising an average of 57.9% of our total energy intake and contributed 89.7% of the energy intake from added sugars [10]. Sugar content in highly processed foods is approximately 5 times more than that found in unprocessed or minimally processed foods. Excess sugar intake can increase hepatic uptake and the metabolism of fructose which can lead to liver lipid accumulation increased cholesterol and decreased insulin sensitivity. In addition, epidemiological studies show that excess sugar consumption is associated with body weight gain, mainly due to sugars inability to decrease hunger levels and therefore lead to increased caloric intakes [11].

The benefits are not exclusive to the Paleo diet

The main issue with the diet is that it is illogical to restrict yourself from healthy, whole foods such as potatoes, oats, grains, and legumes in order to reduce sugar consumption. The two foods are not directly linked and many of the foods on Paleo’s “banned list” are low in sugar whilst being high in fibre, rich in vitamins and minerals and low in dietary fat. It is nonsensical to “treat carbohydrates as if they are the devil”, as referred in one Paleo article when minimally processed carbohydrates sources have a host of health boosting abilities. To advocate a diet whilst knowing that you are limiting your intake of multiple beneficial nutrients and phytonutrients that can significantly improve health is unjust.

Oats can be used as an example. There is a deep research base conveying multiple health benefits attributed to their beta-glucan content and other non-essential components. These benefits range from appetite control, enhanced immune response, and improvements in blood lipid profile and glucose control [12].

A study also stated that limiting whole-grain intake leads you prone to deficiencies in the nutrients these sources are rich in. Calcium, Vitamin D Folate, Magnesium, Fibre, Vitamin E, Potassium, Flavonoids, Selenium, Lignans are Phytosterols are the nutrients of primary concern, and those following a Paleo diet should realise they may be unnecessarily restricting themselves [13].

 The irrational fear of sugar or fructose consumption in moderation is also not based upon evidence. As previously discussed, excess sugar intake can cause health problems, but so can everything when consumed in very high amounts. Following a diet that is so strict on the complete elimination of sugar is unnecessary when you realise small to moderate amounts aren’t shown to impact health. Dose and context is vital. 50g of fructose per day (~100g sugar), a relatively high amount for most people, showed no damaging effect on fasting and postprandial triglycerides, glucose control and insulin resistance [14]. Keeping added sugar limited to roughly 10% of total calories is preferable, and allows for moderation and balanced dietary practices whilst not risking adverse potential downfalls of excess intakes. The Paleo diet is not necessary to achieve this.

  1. Paleo Diet Food List. (2015). Available:
  2. Carbs Needed to Evolve Big Brains. (2015). Available:
  3. Hardy.K. (2015). PALEO DIET: Big Brains Needed Carbs - The importance of dietary carbohydrate in human evolution, The Quarterly Review of Biology
  4. Katz.DL. (2014). Can We Say What Diet Is Best for Health?, Annual Review of Public Health
  5. Meckling.KA et al. (2004) Comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women, The Journal of Clinical Endocrinology & Metabolism
  6. Tay. J et al. (2008). Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects, Journal of The American College of Cardiology
  7. DiGiacomo.DV et al. (2013). Prevalence of gluten-free diet adherence among individuals without celiac disease in the USA: results from the Continuous National Health and Nutrition Examination Survey 2009–2010, Scand J Gastroenterol.
  8. Eating To Break 100: Longevity Diet Tips From The Blue Zones. (2015). Available:
  9. Xia.L. (2006). A hemagglutinin with mitogenic activity from dark red kidney beans, J Chromatogr B Analyt Technol Biomed Life Sci
  10. Steele.EM et al. (2016). Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study, BMJ.
  11. Stanhope.KL. (2016). Sugar consumption, metabolic disease and obesity: The state of the controversy, Crit Rev Clin Lab Sci.
  12. Daou.C. (2012). Oat Beta-Glucan: Its Role in Health Promotion and Prevention of Diseases, Comprehensive Reviews in Food Science and Food Safety
  13. Higdon.J et al. (2003). Whole Grains, Oregon State University
  14. Rizkalla.S. (2010). Health implications of fructose consumption: A review of recent data, Nutr Metab (Lond).
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