Read: The paleo revolution
The modern paleo diet consists of eating mainly unprocessed meat, but includes bacon (which is processed), fish, shellfish, eggs, and most low-energy vegetables (potatoes are taboo, so I wonder what the ancient tribes in South America lived on?).
The diet also allows oils, like olive and canola (What ever happened to the ‘Anti-Canola Lobby?’), avocado and grass-fed butter (I presume this means that the cows producing the milk from which the butter fat was removed, ate grass?).
Nuts and seeds get the nod (except for cashew and peanuts which are classed as very high in fat and ‘easy to eat’ - this is a conundrum because all nuts although very healthy, are rich in fat and all nuts, not just cashews and peanuts, are highly more-ish!).
Most fruits are permitted, although individuals who want to lose weight are warned not to have more than 1-3 fruits per day (Ultimate Paleo Guide, 2014).
All grains and cereals and legumes are banned - which makes me wonder what our ancestors did when they collected seeds from so-called Emmer wheat or the first beans that also originated in South America. Did the Mayans and Incas who discovered maize, potatoes and beans, not eat and thrive on these foods?
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Variation of the Atkins diet
A close look at this paleo diet shows that it is actually a variation of the Atkins diet, in other words basically high-protein, high-fat and very little carbohydrate. So as I have mentioned before, anyone using this type of diet will initially lose substantial amounts of weight, but there is always the problem of sustainability because eating a diet devoid of carbs is difficult for omnivores who have been eating starchy roots and seeds since the dawn of time and depend on these carbs for energy and even variety.
I am not convinced that our Australopithecine ancestors who purportedly stood up on their hind legs on the African veld in the Gauteng area and thus started developing all manners of useful skills like stereoscopic vision and using their hands to make tools and weapons, feasted on high-protein foods like meat and fish all the time.
I am sure they did eat nuts and wild berries and fruits, but probably did not yet have the technology to extract oils from nuts or seeds. So the paleo diet as presented today is just another variation of the Atkins or Prof Noakes or Dukan diets - just made a bit more alluring by reference to the distant past.
Read: Paleo diet: not a diet of logic
One of the latest publications by Caroline Mellberg and her coauthors (2014) working at the Department of Public Health and Clinical Medicine at Umea University in Sweden, investigated the long-term effects of a Palaeolithic-type diet on the health, weight loss and metabolic profiles of obese postmenopausal women over a period of 2 years. The researchers set out to also determine how sustainable the paleo diet is in practice over long periods of time.
The subjects included in the study were 70 healthy postmenopausal women with an average age of 60 years and an average BMI = 33 kg/m2 (i.e. the subjects were all in the obese range), who were divided randomly into a paleo diet (PD) group of 35 women and a control group of 35 women who were instructed to use what is called the Nordic Nutrition Recommendations (NNR) diet. Both diets were consumed ad libitum, which means that no energy restriction or portion control was applied in either group (Mellberg et al, 2014).
The intended paleo diet composition was as follows: 30% of energy was to be provided by protein, 40% from fat particularly mono- and polyunsaturated fats, and 30% of energy from carbohydrates. According to the authors (Mellberg et al, 2014) the diet consisted of lean meat, fish, eggs, vegetables, fruit, berries and nuts (i.e. it was therefore similar to the paleo diet principles listed above). All dairy products, cereals, added salts and refined fats and sugars were excluded.
The composition of the NNR diet provided 15% of energy from protein, 25-30% of energy from fat and 55-60% of energy from carbohydrates, with special emphasis on low-fat dairy products and high-fibre cereals (i.e. a typical balanced, high-fibre diet without refined starches, sugars, sweetened cold drinks and alcohol).
The experimental and control subjects participated in 12 group sessions run by dietitians, trained in the principles and application of each diet, who provide them with information about their specific diet, recipes and how to cook the diet foods. The dietitians also gave talks on healthy habits and behavioural changes.
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The dietary intakes of the two groups were assessed at baseline before commencement of the study period and every month for the first six months for periods of four days using self-reported estimates of intake. Thereafter the subjects were evaluated at 9, 12, 18 and 24 months to determine what they were eating over a period of four days (three days of each assessment period were weekdays and one day was a weekend day to provide a balanced estimate of their food intake).
The researchers also checked how well the participants were sticking to their high protein intake by doing nitrogen assays on urine samples collected from the subjects (the nitrogen content of the urine is related to dietary protein intake) (Mellberg et al, 2014).
Metabolic parameters such as body weight, body fat %, waist circumference measurements and blood fat analyses were conducted throughout the study.
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There were no significant differences in characteristics between the PD and NNR diet groups at the start of the study. No significant differences were found between the two groups in Resting Energy Expenditure (REE), physical activity energy expenditure (PAEE) and total energy expenditure (TEE) which were monitored at regular intervals.
Interestingly both groups ate less food and ingested less energy over the two-year period without there being a significant difference between the groups. At six and 24 months, the PD group ingested 19% and 20% less energy than at the start of the study, while the NNR group reduced their energy intake by 18% and 12% respectively (Mellberg et al, 2014).
Average weight losses were higher in the PD group (namely -6.6kg and -2.6 kg at six and 24 months respectively) compared to a weight loss of 4.6 kg and 2.9 kg for the NNR group at the same times. So although the weight loss was initially 2kg higher in the PD group, at the end of 24 months there was once again basically no difference in the amount of weight lost by the two groups in the last 18 months (2.6kg vs. 2.9kg). Similar findings were obtained for changes in BMI (Mellberg et al, 2014).
Loss of lean muscle mass
An unexpected result was that the PD group lost significantly more total lean muscle mass (-1.3kg vs -0.4kg) than the NNR group (Mellberg et al, 2014). Why this should happen in the group that was supposedly eating more protein, is not clear, but it is possible that the lack of carbohydrates in the PD diet made the subjects use up their body protein for energy.
Weight loss should, if possible, not be accompanied by a loss in lean muscle mass, which is why many sports dietitians recommend that the athletes under their care should ingest carbs not just as fuel but for their so-called ‘protein sparing effects’.
Waist circumference measurements decreased in both groups with a more significant decrease in the PD group at six months.
Improved blood pressure, LDL- and total cholesterol
The PD group also had the most significant decrease in triglyceride levels over time. In addition all the participants in both groups experienced improvements in blood pressure, heart rate, LDL-cholesterol and total cholesterol. The weight loss and the two different diets made no difference to fasting glucose or fasting insulin concentrations, despite the fact that the PD was practically devoid of carbs, while the NNR diet contained high-fibre carbohydrates that provided 50% or more of the energy (Mellberg et al, 2014).
An important finding was that the target intakes of the ‘critical’ foods were not achieved in either group. The PD group did not achieve their target protein intake (30% of energy from protein) at six or 24 months and the NNR group did not achieve their target carbohydrate intake (55-60% of energy) at these points in time either (Mellberg et al, 2014).
The authors of the study suggest that following reasons why their PD subjects did not manage to eat as much protein as was specified, namely:
- protein-rich foods tend to be expensive
- social factors that influence female food choices (men may happily eat a 500g or even a 750g steak, but most women shudder at the thought)
- women may basically not like eating protein foods as much as men do
- interference from other diet components (see below)
(Mellberg et al, 2014)
One factor that may interfere with high protein intake was the inclusion of polyunsaturated fats from plant oils, avocado and nuts in the PD diet. These polyunsaturated fats increase satiety and may reduce appetite and make it difficult to achieve a really high protein intake.
The study conducted in Sweden by Mellberg and her team (2014) with postmenopausal women showed that both the paleo and the NNR diets helped the women lose weight and that over a long period there were no really striking differences in performance, except for the highly improved triglyceride levels in the PD group.
This study once again showed that it appears to be difficult for modern people living in the real world to maintain high protein or high-fibre intakes for long periods of time. The researchers suggest that additional studies are required to pinpoint if it is the high protein intake or the high polyunsaturated fat intake in the paleo diet that causes the weight loss and the improved triglyceride levels.
Perhaps it would benefit humanity even more if we could turn back the clock not only on our diets, but on our physical activity. Instead of slumping in front of the TV or our PCs, we should be engaging in mammoth hunts at sub-zero temperatures or running for our lives to outdistance a predator, or walking vast distances to collected wild seeds, nuts and plants for our cave. It is possible that a substantial increase in physical activity could make an even greater difference to our weight loss and our health!
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(References: Mellberg C (2014). Long-term effects of a Palaeolithic -type diet in obese postmenopausal women: a 2-year randomized trial. European Journal of Clinical Nutrition advance online publication, 29 January 2014: doi:10.1038/ejcn/2013/290; Ultimate Paleo Guide (2014). Ultimate Paleo Guide. The Paleo Diet made simple. )
(Photo of woman measuring body from Shutterstock)
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