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 

Diets that do and diets that don’t: Part 1 – The New Atkins Diet

By Tamzyn Murphy

BSc Med(Hons) Human Nutrition and Dietetics, RD

 

People across the globe are getting fat and desperate – a profitable situation for those peddling fad diets. Obviously conventional nutritional wisdom has failed us – eating fewer calories (particularly less fat) and burning more by exercising doesn’t cut through the flab. It appears that our will-power just isn’t strong enough to overcome the hunger that goes with this kind of advice. Authorities’ recommend that we base our eating on carbohydrate-filled food, with less than 30% of calories from fat and about 15-20% from protein. Much of these carbs come from refined starches and sugar, making our insulin levels skyrocket, which puts our bodies into fat-storage mode and makes us even hungrier. But before that sends you running into the arms of the latest diet, make sure you know which ones work and which are doomed to failure.

 

New Atkins Diet[i]

Atkins is a low carb diet – one of the stricter versions. You shouldn’t be hungry on this diet though and calories aren’t restricted. Most people think low carb diets are high in protein and low in fat. Thankfully this isn’t usually the case – fat keeps hunger at bay and the right types promote good health; while excessive protein could be dangerous. Low carb diets are typically high in fat (60% or more) and moderate in protein (about 25%). The aim is to keep insulin levels low by restricting carbs, thereby reducing hunger and fat-storage, and retraining the metabolism to burn fat instead of carbs.  They’re great for weight loss. And recent evidence indicates they may also reduce heart disease, diabetes and metabolic syndrome risk.[ii] They’re particularly beneficial for those with insulin resistance or pre-diabetes.[iii]

There are four phases to the New Atkins diet – an updated version of Atkins. Phase 1 is really strict, allowing only 20g of carbs a day – mainly from low carb veggies. As you move through the phases you gradually increase the amount of carbs you’re allowed according to the “Carb Ladder” – adding nuts, seeds, low carb fruits, certain dairy products and some legumes. During this process you’re supposed to learn what your individual carbohydrate tipping point is – eat less carbs and you lose weight, more and you gain weight. By the end you should have lost all of your excess weight and know how to make this diet a permanent lifestyle fixture to maintain your weight and optimise health.

Critics claim the high fat content, particularly saturated fat, of low carb diets is bad for heart health but recent evidence refutes this.[iv] Others worry that excessive protein puts strain on the kidneys and leaches calcium from the bones, but the protein content of these diets isn’t typically excessive and there’s no evidence that it negatively impacts on kidney[v] or bone health.[vi] Where casual Atkins dabblers go wrong is they use it as an excuse to pass up on vegetables, gorge in processed food and deep fry everything.

 

References

[i] New Atkins. 2011 

[ii] Azadbakht L, Izadi V, et al. Effect of a High Protein Weight Loss Diet on Weight, High-Sensitivity C-Reactive Protein, and Cardiovascular Riskamong Overweight and Obese Women: A Parallel Clinical Trial. Int J Endocrinol. 2013;2013:971724. Published online: Aug 2013 

and

Noakes TD, Windt J. Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. Br J Sports Med 2017;51:133-139 

[iii] Feinman RD, Pogozelski WK, et al. Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. Nutrition 2015;31:1-13

[iv] Siri-Tarino PW, Sun Q, et al. Saturated fat, carbohydrate, and cardiovascular disease. Am J Clin Nutr 2010;91:502–9

and

Harcombe Z, Baker JS, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart 2015;2:e000196.

[v] Brinkworth GD, Buckley JD, et al. Renal function following long-term weight loss in individuals with abdominal obesity on a very-low-carbohydratediet vs high-carbohydrate diet. J Am Diet Assoc. 2010 Apr;110(4):633-8 

[vi] 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.