Food markets, restaurants, publishers – all want to benefit from the boom. A discounter, who confesses “that he loves food”, says on his website: “Already in the Stone Age vegetables were valued for being very nutritious”. Raw instead of roasted is now the motto. Pizza from cauliflower and coconut flour instead of white flour. Stone Age people were not yet running agriculture systems and carried a different set of genes which made cereals for them poorly digestible. Therefore, as part of the Paleo diet cereal products are supposed to be dispensed with. Today we carry, instead of one, up to twelve amylase genes in our genome and we tolerate bread quite well – gluten intolerance aside.
Computer replaces club
The arguments made by our fans of the Stone Age have at first a positive ring to them. Primitive man for more than two million years nourished himself with lots of meat and ate raw fruit and vegetables. Dairy and grain products, edible oils and salt on the other hand have only been on our consumption list for about 10,000 years. How it was that hunter-gatherers fed themselves at that time can only be guessed at based on tool finds. Certainly though, beetles, carrion and probably sometimes their neighbours were to be found on the menu. We no longer live and work as did our Stone Age ancestors. Our food supply at the time had to meet very different requirements than it does today. The hunt for an animal was long and exhausting – not comparable to doing work on a PC.
The liver loves Paleo
One study by Ryberg et al. from University Umeå in Sweden examined the impact of a Paleo diet on the triglyceride levels in postmenopausal women. All subjects were healthy but, in having an average BMI of 27, were overweight. For five weeks the women fed themselves along the lines of Stone Age people. For breakfast, midday and dinner there were 30 parts each of proteins, 40 parts fat (with mainly polyunsaturated fatty acids) and 30 parts carbohydrates, supplemented by daily rations of 40 g nuts.
For those who saw this as not being enough, extras were able to be added to the diet at will – using self-prepared “Stone Age food” according to predefined recipes. One would assume that the high meat consumption led to a deterioration of numerous parameters. Amazingly, the opposite was the case. On average, the women had dropped 4.6 kilograms. Their BMI had fallen by 4 percent. Their heart rate had significantly reduced from an average of 74 to 64 beats per minute and their blood pressure was also slightly lower. Compared with their previous diets, fat intake had increased, but “healthy” fats were mainly consumed. There was in particular an increase by 122 percent in the proportion of polyunsaturated fatty acids. The intake of saturated fat had decreased by 57 percent, carbohydrate intake by 58 percent.
The diet had further positive metabolic effects. Triglyceride content of the liver fell by almost 50 percent, fasting insulin and glucose levels were lower and reduced C-peptide-secretion was recorded. It’s presumable that these effects are also due to improved insulin sensitivity. Fat decomposition in the liver is particularly important in postmenopausal women because the redistribution of body fat from central areas to the periphery has a protective effect against the development of diabetes and cardiovascular disease. Although the women were not limiting their calorie intake, they took in an average of 520 kcal (2153 kj) less. The Paleo diet, in being high protein, increases the feeling of satiety, as well as heat and thus energy production. Since the diet is free of refined sugars, hepatic lipogenesis and the risk of non-alcoholic fatty liver disease, particularly through fructose, drops. The study can be taken as an indication that a high-protein and low-carbohydrate diet may have favourable metabolic effects. However, many questions remain unanswered. What are the effects of increased consumption of meat as part of a long-term diet? Are the effects also transferable to men and younger women?
Stone Age diet for diabetics
Whoever understands the Paleo diet to mean that he or she should eat half a pig without toast every day is certainly getting things wrong. By contrast, doing a lot of movement out in the open air, having unsaturated fatty acids, lots of nuts and little carbohydrate are certainly metabolically useful. You can call it Paleo, or just healthy eating.
In a randomised cross-over study by Bligh et al. [Paywall] healthy volunteers at various time points were provided with three different meals: two Paleo-meals and a reference meal. Over a period of 180 minutes, plasma glucose, insulin, glucagon-like peptide (GLP-1), glucose-dependent insulinotropic peptide (GIP) and peptide YY (PYY) were measured. These parameters allow a conclusion to be drawn on the risk level for developing metabolic disorders. The satiety of the subjects was determined by means of an electronic visual analogue scale (EVAS).
GLP-1 and PYY were significantly increased in both Paleo groups compared to the reference group, and the feeling of satiety was also higher in the Paleo group. The GIP concentrations were low, which prevents insulin resistance and fat accumulation. Glucose and insulin levels were not significantly different between the three groups. The incretin levels in the Paleo groups were significantly elevated, which among other things contributes to more rapid satiety. “The results lead to the assumption that the Paleolithic diet could lead to a lower risk of being overweight,” was the conclusion of the authors. In a study by Manheimer et al. [Paywall] it was also shown that Paleo-nutrition leads to higher weight loss and lipids, blood pressure and blood sugar levels are improved more than by other diets.
Does caveman become fat man?
Thus numerous studies attribute to the Paleo diet positive effects on weight and metabolism. One study on the other hand considers this diet to even be dangerous. Study leader Sof Andrikopoulos is president of the Australian Diabetes Society and warns: “This type of diet is not recommended, especially for people who are already overweight or practising a mainly sedentary lifestyle. For people who are suffering from diabetes or a diabetes precursor, a ‘low-carb, high-fat’ nutrition pattern is risky”.
The objective of the study was to establish whether a ‘low-carb, high- fat’ nutrition pattern (LCHF) is suitable for people with pre-diabetes and whether it improves their blood values. The study, however, was not carried out on humans, but on obese mice with pre-diabetes. One group received low-fat, high-carb feeding (60 percent fat, 20 percent carbohydrate), the other was fed a low-fat diet with only 3 percent fat and correspondingly higher carbohydrate content. After 8 weeks, the animals in the LCHF group had increased in weight by 15 percent, their body fat percentage had doubled, their insulin levels were increased and insulin resistance had exacerbated.
The study raises many questions. It is totally unclear whether the animal results are transferable to humans: a critique that the study leader takes on board without opposition. Nonetheless, the working group had not implemented the principles of the Paleo diet in their study. The point is not to eat a lot of fat and little carbohydrates, but to pay attention to the quality of food and its preparation as well as to eat a lot of vegetables. All this was not given to the mice. The animal feed as used in the study is more like an Atkins diet. On the website of the University of Melbourne Andrikopoulos warns in written form and in a video against the diet – phrased in short: “Paleo Diet = weight gain “.
In summary, the question arises whether the term “diet” is at all suitable for a “Stone Age form of nutrition”. A diet is adhered to over a certain period, Paleo is more a philosophy of life, comparable to vegetarian or vegan diets. “Meat is my vegetable” is however only a part of this philosophy.