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An objective look at popularised diets

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With society’s dramatic increase in the incidence of weight-gain and obesity and the associated risk of chronic diseases, individuals may seek to resolve this challenge and are often at the mercy of popularised diets.

Popular diets are usually “talked about”, not only in the health arena but also very much in the public sphere. This is because they are often controversial, attracting supporters and objectors at both sides.

Here, we aim to take an objective exploration of the merits and caveats of popular diets including Paleo, Mediterranean and Low-Carbohydrate-High-Fat (LCHF) diets. 

Paleo Diet

The Paleo Diet - also known as the Caveman or Hunter-Gatherer diet is designed to replicate the diet of our pre-agricultural ancestors. It is named after the Paleolithic period, a time in history which spanned from approximately 2.5 million years ago and until 10 000 years ago.[1] Paleo advocates argue our bodies haven’t evolved quickly enough to digest and appropriately handle foods of the modern age. This caveman style of eating has been a growing trend over the last couple of years, and ‘Paleo’ was the most “googled” diet-related term in 2014.[2

What can you eat?

Animal protein, seafood, fruits and non-starchy vegetables, eggs, nuts, seeds and oils like olive or coconut oil.

What can’t you eat?

Processed foods, refined sugar, vegetable oils, salt, grains, potatoes, legumes and dairy.  

Pros:

  • Based on wholefoods - actively removes processed foods and encourages the consumption of lean meats, fruits, vegetables and nuts providing protein, vitamins, minerals, phytochemicals, fibre and monounsaturated fat.
  • Avoidance of refined cereals and sugars - a lower glycaemic index (GI) diet is associated with improvement in risk factors associated with metabolic syndrome in the short-term.[1]
  • Encourages home cooking- allowing us to reconnect with food and return to the kitchen. 
  • No kilojoule counting - does not place limits on how much you can eat which may potentially lead to disordered eating patterns.
  • May be environmentally friendly - true Paleo advocates will source their meats from sustainable and local sources.

Cons:

  • Restricts food groups - cutting out whole food groups, such as grains, legumes and dairy may not only take the joy out of eating, but also removes nutritional aspects of these foods (if not strictly seeking out nutrients from ‘allowed food groups’).
  • Whole grains and legumes are avoided - a substantial body of evidence has associated whole grain and legume intake with disease risk reduction, as these are both a valuable source of fibre and phytonutrients, and provide important prebiotic benefits for our digestive health.[3,4,5]
  • Increased intake of meat - excess consumption can be problematic; the available evidence reveals a positive association between the consumption of red meat, particularly processed meat, and all-cause mortality.[6
  • Difficult to replicate in modern times - the translation of evolutionary nutrition data is challenging, as our current lifestyles do not lend themselves to a “hunter-gatherer” style. Also there is no single Paleolithic nutritional pattern because the composition of macronutrients varied depending on geographical location and climate.[1]

Bottom line

Encouraging a wholefood diet with higher intake of fruit, vegetables, leaner meats and nuts, as well as cutting out highly processed foods would provide considerable health benefits. However, such strict diets may be unsustainable and it is less clear whether the avoidance of cereals and dairy products is a prerequisite for the optimal control of metabolism. There is little research on the health benefits in the longer term.[1]

Mediterranean Diet

Unlike the Paleo diet, the Mediterranean Diet is largely plant-based and encourages the consumption of legumes. This traditional dietary pattern is associated with longevity and identified in the early 1960’s in countries residing in and around the Mediterranean Sea including Greece, Southern Italy and Spain.[7] In these countries there was a reduced risk of coronary heart disease (CHD) when compared to Northern European countries and the USA.[8]

What can you eat?

High intake of olive oil, vegetables, fruits, complex grains, nuts and legumes; moderate intakes of fish, dairy (mostly cheese and yoghurt) and red wine.[9]

What can’t you eat?

Limits meat and processed foods [9].

Pros

  • Does not promote exclusion - includes all major food groups encouraging the consumption of a range of bright and colourful anti-inflammatory and antioxidant rich foods. With less emphasis on exclusions, the diet is not as restrictive as most.[7]
  • Heart friendly - the diet is associated with a decreased risk of morbidity and mortality associated with cardiovascular disease, likely due to a diet rich in anti-inflammatory and anti-atherogenic foods including extra virgin olive oil (EVOO), vegetables and fruits including tomato, garlic, onion, omega-3 fatty acids, as well as the consumption of legumes - a valuable source of fibre and phytonutrients.[5, 10,11,12]
  • Red wine can be enjoyed - red wine is rich in polyphenols and resveratrol and can be enjoyed with meals in moderation.[9]
  • Emphasis on fresh seasonal produce - produce is purchased from local markets and cooking is encouraged as opposed to eating take-away foods. 

Cons

  • Portions are not specified - therefore sizes are interpreted by the subjective meaning of “high”, “moderate” and “low” which may not necessarily promote weight maintenance especially in individuals who are unable to practice portion control. 
  • Consumption of alcohol - wine is encouraged in moderation, which may not be appropriate or not tolerated in certain individuals. 
  • Unsuitable for time-poor - may not be conducive to a time poor individual as requires fresh produce and preparation of meals from scratch. 

Bottom line 

Following this diet extends to the bigger picture of the Mediterranean lifestyle that emphasises community, stress reduction and strong social support for increased wellbeing. Like all diets, it’s important to consume in moderation, particularly red wine. Overall, the largely plant-based diet has considerable robust research to support its benefits in reducing cardiovascular disease risk. 

Low-Carbohydrate, High-Fat (LCHF)

Whilst the Mediterranean-style diet is not designed to promote significant weight loss, LCHF diets, such as the Atkins Diet have been “celebrity-ised" for promoting quick weight loss. The premise behind this diet is the higher fat and protein intake may encourage enhanced satiety to allow for a decreased food intake.[13]

What can you eat?

High-fat foods such as butter and cream as well as high-protein foods such as beef, chicken, pork, eggs and fish.

What can’t you eat?

Limits carbohydrate rich foods such as breads, pasta, rice, potatoes, fruit, and starchy vegetables.

Pros

  • Weight loss may be more attainable - higher fat and protein diets enhance satiety and promote ketosis.[13] This was particularly pertinent in obese subjects, a study found obese individuals with metabolic syndrome lost more weight on a low-carbohydrate diet than on a kilojoule and fat-restricted diet, as well as an improvement in insulin sensitivity and triglyceride levels.[17]
  • Better blood sugar management - a lower intake of carbohydrates can lead to better insulin and blood sugar management, as well as improvements in various markers of cardiovascular disease risk in diabetic individuals.[9]
  • Preserves lean body mass - research has revealed consumption of protein can effectively preserve lean body mass during weight loss.[15]

Cons

  • Possible adverse effects associated with ketosis - such as weakness, fatigue, constipation and headaches when compared to those following a low-fat diet.[16] Individuals should be monitored by a healthcare professional.
  • May affect psychological function - LCHF diets may alter serotonergic expression and adversely affect mood and cognition.[14]
  • Inappropriate for individuals with renal disorders - diets high in protein may increase acid load in the kidneys, increasing the risk for stone formation and decreasing calcium balance leading to a risk for bone loss.[18
  • Not all dietary fat is created equal - the balance of available evidence suggests that reducing saturated and trans fats, and replacing them with polyunsaturated fats will reduce the risk of cardiovascular and CHD.[20
  • Lowered endurance in athletes - carbohydrate intake can enhance training capacity as it can maintain blood glucose levels and maximise glycogen scores.[21

Bottom Line

A diet higher in fat and lower in carbohydrate may be of great interest to overweight individuals. Weight loss had a positive effect on various biomarkers of disease, and improvements in metabolic markers were observed irrespective of the method of weight loss.[19] Individuals should also be cautious in the longer-term, due to increased acid load to the kidneys and higher fat content, and may chose to balance out their diets by increasing their intake of vegetables and fruits. 

Conclusion

No one diet fits all. Many diets remain a contentious topic among both the proponents and opponents. That said, there are healthier ways to interpret the above diets with emphasis on whole, natural foods including fresh fruits and vegetables, lean proteins, dairy, whole grains and legumes, whilst allowing for flexibility to optimise health benefits.

 

References

  1. Manheimer E, van Zuuren E, Fedorowicz, Z, et al. Paleolithic nutrition for metabolic syndrome: systematic review and meta-analysis. J Clinical Nutr 2015;102:922-932. [Abstract
     
  2. Friedman M. The Paleo diet and the insanity workout dominated Google search in 2014. Redbook 2014. Viewed 8 March 2016. [Link]
     
  3. Helnæs A, Kyrø C, Andersen I, et al. Intake of whole grains is associated with lower risk of myocardial infarction: the Danish Diet, Cancer and Health Cohort. Am J Nutr 2016;103(3). [Abstract
     
  4. Jonnalagadda S, Harnack L, Liu R, et al. Putting the whole grain puzzle together: health benefits associated with whole grains - Summary of American Society for Nutrition 2010 Satellite Symposium. J Nutr 2011;141(5):1011S-1022S. [Full Text
     
  5. Messina V. Nutritional and health benefits of dried beans, Am J Clin Nutr 2014;100(1):437S-442S. [Full Text
     
  6. Larsson S, Orsini N. Red meat and processed meat consumption and all-cause mortality: a meta-analysis. Am J Epidemio 2014;179(3):282-289. [Full Text
     
  7. Davis C, Bryan J, Hodgson J, et al. Definition of the Mediterranean diet: a literature review. Nutrients 2015;7(11):9139-9153. [Full Text
     
  8. Menotti A, Kromhout D, Blackburn H, et al. Food intake patterns and 25-year mortality from coronary heart disease: cross-cultural correlations in the seven countries study. Eur J Epidemiol 1999;15(6):507-515. [Abstract
     
  9. Ajala O, English P, Pinkney J, et al. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr 2013;97:505-516. [Full Text
     
  10. Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. New Eng J Med 2013;368:1279-1290. [Full Text
     
  11. Martínez-Gonzáleza M, Salas-Salvadób J, Estruch R. et al. Benefits of the Mediterranean diet: insights from the PREDIMED study. Prog Cardiovasc Dis 2015;58(1);50-60. [Abstract
     
  12. Guasch-Ferré M, Hu F, Martínez-González M, et al. Olive oil intake and risk of cardiovascular disease and mortality in the PREDIMED Study. BMC Med 2014;12(78):1-11. [Full Text
     
  13. Pesta D, Samul V. A high-protein diet for reducing body fat: mechanisms and possible caveats. Nutr Metab 2014;11(1):53. [Full Text
     
  14. Halyburton A, Brinkworth G, Wilson C, et al. Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance. Am J Clin Nutr 2007;86(3):580-587. [Full Text
     
  15. Kim J, Sands L, Slebodnik M, et al. Effects of high-protein weight loss diets on fat-free mass changes in older adults: a systematic review. FASEB 2014;28(1);Suppl 371.5 [Abstract
     
  16. Yancy W, Olsen M, Guyton J, et al. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial. Ann Int Med 2004;140:769-77. [Abstract
     
  17. Samaha F, Iqbal N, Seshadri P, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. New Engl J Med 2003;348(21):2075-2081. [Full Text
     
  18. Reddy S, Wang C, Sakhaee K, et al. Effect of low-carbohydrate high-protein diets on acid–base balance, stone-forming propensity, and calcium metabolism. Am J Kid Dis 2002;40; 265-274. [Abstract
     
  19. Clifton P, Keogh J, Noakes M, et al. Long-term effects of a high-protein weight-loss diet. Am J ClinNutr 2008;87:23-29. [Full Text
     
  20. Hooper L, Mann J. Observational studies are compatible with an association between saturated and trans fats and cardiovascular disease. Evid Based Med 2016;21(1):37 [Full Text
     
  21. Hassapidou M. Carbohydrate requirements of elite athletes. Brit J Sports Med 2011:42(e2). [Abstract

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Gemma_Shelton's picture
Gemma Shelton

Gemma is a qualified naturopath, holding a degree in Health Science majoring in Naturopathy. She is currently working in a naturopathic role at an Australian nutraceuticals company, advising customers with naturopathic advice, as well as providing support to the product development and regulatory team. Gemma has previously spent time living in Japan, where her interest in natural health was originally sparked when she was introduced to traditional kampo medicine. She also holds a BA in Public Communication, with previous experience consulting in nutrition communications.