Three new diets get put to the test
New diets – or new versions of old diets – are published every year and some appear, at first glance, to have scientific credibility. We look at three recent, popular diets and see if they deliver what they promise.
The Paleolithic or ‘Stone Age’ diet
What is it?
Based on the diets of early man prior to the development of agriculture, this diet advocates eating meat, fish, vegetables, fruit, roots and nuts but excluding grains, legumes, dairy products, salt, refined sugar and processed oils from your diet. Two small studies have shown health benefits from adopting this diet,1,2 and proponents claim this way of eating offers freedom from ‘diseases of affluence’ such as diabetes, heart disease, 1,2 but the National Health Service in the UK has dismissed it as a fad.3
Advocates minimally processed foods, eaten in as close to their natural state as possible.
This is not a realistic diet; it limits your intake of certain major food groups.
For more information: paleodiet.com
The blood type diet
What is it?
Naturopath Peter J D’Adamo, author of Eat Right 4 Your Type and The GenoType Diet, claims your blood type is crucial in determining the best diet for you; he advocates different diets depending on whether you have type A, B, O or AB blood. Drawing on research conducted in the 1950s by immunochemist and blood-type anthropologist William C Boyd that analysed the genetic makeup of blood groups, Adamo claims that blood group O is the earliest human blood group and is based on that of our hunter forebears; A dates from the beginnings of agriculture; and B stems from our nomadic ancestors. With this in mind, D’Adamo claims, we are best served by eating the foods most commonly associated with our blood group ancestors.
Though Adamo advises that people of certain blood types avoid specific foods, the diet he proposes does not restrict your intake of entire food groups and advocates eating fresh, unprocessed foods and reducing your consumption of refined foods.
This diet is not backed up by scientific evidence.
For more information: dadamo.com
The South Beach Diet
What is it?
Devised by a prominent Miami cardiologist and dietitian, Dr Arthur Agatston, the South Beach Diet classifies ‘good carbs’ (those with a low GI) and ‘good fats’ (no trans-fats) in order to avoid the hunger spikes that can make sticking to a diet so hard.
Several scientific studies have shown favourable results in participants with regard to weight loss. The diet focuses on eating fresh fruits, vegetables, whole grains and lean protein, and does not exclude any major food group.
The initial phase of the diet is quite restrictive and can result in weight loss resulting from loss of water rather than reduction of body fat, which in turn can disrupt the body’s electrolyte balance.
For more information: southbeachdiet.com
References: 1. Lindeberg S, Jönsson T, Granfeldt Y, Borgstrand E, Soffman J, Sjöström K, Ahrén B (September 2007). A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia 50 (9): 1795–807. doi:10.1007/s00125-007-0716-y. PMID 17583796 2. Jönsson T, Ahrén B, Pacini G, Sundler F, Wierup N, Steen S, Sjöberg T, Ugander M, Frostegård J, Göransson L, Lindeberg S (2006). A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs. Nutrition & Metabolism 3 (39): 39.doi:10.1186/1743-7075-3-39. PMID 17081292. PMC 1635051 3. nhs.uk/news/2008/05May/Pages/Cavemanfaddiet.aspx