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Diets that do and diets that don’t: Part 4 – The Dukan Diet

By Tamzyn Murphy

BSc Med(Hons) Human Nutrition and Dietetics, RD

 

Unlike the typical low carb diet, Dukan is high in protein (starting at 40% of calories) and low in fat (20% of calories). It’s big on rules and the restrictive phases are incredibly strict – any indiscretion is seen as a major failure. The idea is to replace much of your dietary carbs and fat with protein, which is filling, low in calories and takes time and work to digest. Studies on low carb, low fat, high protein diets show that you’ll naturally eat far fewer calories, feel full and you’ll likely experience metabolic benefits, including improved cholesterol, blood fat, glucose and insulin levels, thereby possibly reducing heart disease, diabetes and metabolic syndrome risk.[i], [ii] But weight loss benefits don’t appear to out-do other diets.

There are four phases. Phase one lasts about 5 days and consists almost exclusively of protein food – meat, seafood, poultry, eggs, vegetable-protein and fat-free dairy. No vegetables. Phase two allows non-starchy veg to be added to phase one’s protein foods, on every alternate day, and continues until you’ve lost the weight. The third phase last a few months and allows all the protein food and non-starchy veg you like, as well as limited fruit, whole grain bread and cheese. Phase three also allows two starch servings (e.g. pasta) and two anything-you-want meals each week. Phase four: eat what you like six days of the week, bearing in mind what you learnt during phase 3. On day seven you must eat like you did in phase one. A daily oat bran serving forms part of each phase, probably in an attempt to increase the fibre content of the diet.

Dukan’s excessive protein may increase your risk of gout[iii] and put strain on the kidneys[iv]. And a high protein and low fibre diet is bound to give you constipation. Cutting out entire food groups may put you at risk for nutritional deficiencies. So if you’re insistent on following this diet, it’s probably prudent to take a complete vitamin and mineral supplement, especially during the first two very restrictive phases. Phase four’s sudden dietary freedom may leave you directionless and reverting back to your old ways, resulting in rebound weight gain. And with all the expensive protein you’re guzzling, prepare for dent in your bank balance; as well as a conscience-prick at the number of animals that are being killed and the environmental impact of a carnivorous diet.

References

[i] Dumesnil JG, Turgeon J, et al. Effect of a low-glycaemic index–low-fat–high protein diet on the atherogenic metabolic risk profile of abdominally obese men. British Journal of Nutrition. Nov 2001;86(5):557-68 

[ii] Farnsworth E, Luscombe ND, et al. Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women.

[iii] Torralba KD, De Jesus E, Rachabattula S. The interplay between diet, urate transporters and the risk for gout and hyperuricemia: current and future directions. Int J Rheum Dis. 2012 Dec;15(6):499-506 

[iv] Juraschek SP, Appel LJ, et al. Effect of a high-protein diet on kidney function in healthy adults: results from the OmniHeart trial. Am J Kidney Dis. 2013 Apr;61(4):547-54

Diets that do and diets that don’t: Part 3 – The Blood Group Diet

By Tamzyn Murphy

BSc Med(Hons) Human Nutrition and Dietetics, RD

 

Eat right for your type, by naturopathic doctor Peter D’Adamo, was first published almost 20 years ago, but it’s more popular than ever. It advises people to eat certain foods and avoid others based on their blood type – O, A, B or AB. According to D’Adamo, your blood type determines how your body digests lectins (anti-nutrient proteins found in certain foods). Apparently, eating lectins that are incompatible with your blood type causes a host of adverse health effects, from bloating and inflammation to weight gain. Allegedly, your blood type even determines what exercise suits you best.

 

Foods are categorised as ‘highly beneficial’ (with medicinal effects), ‘neutral’ (acting as a food) or ‘avoid’ (toxic) for each blood type. O (“for old” – humanity’s oldest blood line) types are told to follow a meat-based diet and vigorous exercise programme.  Type A (for “agrarian”) should eat vegetarian food and exercise gently. B types are thought to have nomadic genes and digestive systems that can tolerate many foods, except, amongst other things, wheat, corn and lentils. Bs should exercise moderately. D’Adamo says the “modern” AB blood type has a sensitive digestive tract and should avoid meat and poultry but can enjoy seafood, tofu, dairy, and most fresh produce. ABs should do calming exercises.

 

People probably love this diet because it sounds scientific; but nothing could be further from the truth. There is absolutely no evidence that some foods or exercises are good for people of one blood type and “dangerous” for another. It appears that D’Adamo has randomly bestowed fictional characteristics upon people of different blood types and thumb-sucked foods to put on his ‘beneficial’ and ‘avoid’ lists. If the diet has worked for you it’s probably because all blood types are encouraged to eat real, whole and natural foods in place of processed, sugary and fatty choices, and exercise is always recommended. These are prudent health recommendations that’ll work for anybody. Also each of the four diets loosely resembles a diet that has been shown to have weight loss benefits: The O diet’s a variation on the typical high protein, low carb diet; A’s vegetarian; B’s somewhat similar to the Mediterranean and low GI/GL diets and AB is Pescatarian. In my opinion, the blood type diet’s a perfect example of a fad diet that profits from people’s desperation. If it works, it’s not for the reasons you think.

 

References

[i] WebMD. The eat right for your blood type diet. Sep 2013

[ii] Eat right for your type. www.dadamo.com. Sep 2013

Diets that do and diets that don’t: Part 2 – The Paleo Diet

By Tamzyn Murphy

BSc Med(Hons) Human Nutrition and Dietetics, RD

 

The Paleo diet, founded by researcher Loren Cordain (PhD), is based on what our caveman ancestors ate. It includes only the foods we’ve eaten for most of human history; which we’ve evolved to eat. Like Atkins, Paleo is a low carb, moderate protein, high fat diet. You’re allowed as much meat, fish, poultry, eggs, natural fat (e.g. butter, olive oil, avocado) and non-starchy vegetables as you like. Unlike Atkins, Paleo allows any other foods that our caveman ancestors ate, like any root vegetables, nuts, seeds and fruit.  We only became dependent on farmed foods, like grains, legumes (beans, peas, lentils) and dairy, relatively recently – less than 500 generations ago – with the advent of agriculture. So our genes haven’t had much time to adapt to problem compounds in these foods, theoretically causing inflammation and weight gain.

Indeed, grains and legumes contain anti-nutrients (like lectin and gluten) which interfere with nutrient absorption, irritate intestinal lining (promoting leaky gut) and yield other toxic effects. Cereal grains, particularly wheat, are the worst.[i] So there’s a case to be made for limiting or even eliminating them. But legumes’ anti-nutrients are largely inactivated by cooking at high temperatures, which makes them relatively safe[ii]. Plus legumes contain numerous beneficial compounds.[iii] They’re also are an important protein source – particularly important for vegetarians, vegans and the poor; not to mention ethical and environment-friendly meat-replacements. There’s no evidence that legumes increase weight gain. Research shows that dairy doesn’t have inflammatory[iv] or weight promoting effects[v]. In fact it may do the opposite.

So, the theory behind Paleo is sound – eat whole, unprocessed food as much as possible. But including moderate amounts of dairy and legumes may offer more benefits than risks. Paleo loses points on the expense-front, and due to the lack of dairy you might want to supplement with calcium and vitamin D, unless you’re getting plenty of other calcium rich foods and enough sunshine.

 

References

[i] Cordain L. Cereal Grains: Humanity’s Double Edged Sword. Simopoulos AP (ed): Evolutionary Aspects of Nutrition and Health.Diet, Exercise, Genetics and Chronic Disease. World Rev Nutr Diet. Basel, Karger, 1999;84:19-73

[ii] Pusztai A, Grant G. Assessment of lectin inactivation by heat and digestion. Methods Mol Med. 1998;9:505-14 

[iii] Bouchenak M, Lamri-Senhadji M. Nutritional quality of legumes, and their role in cardiometabolic risk prevention: a review. J Med Food. 2013 Mar;16(3):185-98 

[iv] Labonté MÈ, Couture P, et al. Impact of dairy products on biomarkers of inflammation: a systematic review of randomized controlled nutritional intervention studies in overweight and obese adults. Am J Clin Nutr. 2013 Apr;97(4):706-17 

[v] Abargouei AS, Janghorbani M,  et al. Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. Int J Obes (Lond). 2012 Dec;36(12):1485-93