Paleo Diets Have Peaked - Now the Skeptics Grow Louder

Two major sources (Aeon Magazine and BBC Future) both ran skeptical articles about the paleo diet trend on the same day. Haters gonna hate. The reality is that a diet rich in vegetables (non-starchy), lean meats, nuts, eggs, and fruit is healthy and satiating, so one will lose weight. If you eat processed food-type products (not real food), you will likely be overweight and more prone to several diseases, including diabetes, cardiovascular disease, and cancer.

So "paleo" is a fad, but it's founded on solid principles and solid research.

Against the Grains

A carbs-rich diet has been blamed for the alarming explosion of obesity and chronic disease. What does the science show?

by Melinda Wenner Moyer | 17 June 2014

A Kellogg's magazine advert, 1952. Photo by The Advertising Archives

Melinda Wenner Moyer is a science and health journalist. She teaches at the City of New York’s graduate school of journalism, and is the parenting columnist for Slate. She lives in Cold Spring, NY.

A decade ago, I said goodbye to wheat. I had been carrying around 15 extra pounds since high school and I was sick of it. A friend claimed that going wheat-free helped her lose weight and feel more energetic. A diet that didn’t require counting calories? Sounded good to me, so I gave it a shot. Six months later, those 15 pounds, close to seven kilos, were history.

Slowly, wheat found its way back into my world – oh how I missed bread! – and in 2009 I decided I was done. I haven’t regained much of the weight, nor do I feel different now. I can’t help but wonder, then, why my diet worked. Was it that my body truly functioned better without wheat? Was the claim true that carbohydrates, especially grains, promoted weight gain more than other types of foods?

Anti-carb rhetoric has been around for a long time, but it’s gotten fierce these past few years, and the public is lapping it up. Numerous best-sellers blame wheat, gluten and sugar for obesity, neurological disorders, and other chronic diseases. Carb critics fall into two basic camps: some make biochemical arguments, suggesting that the way our body processes carbs produces unique and harmful health effects, while others say carbs symbolise humanity’s fall from grace – that every time we stuff our faces with cookies, pasta and bagels, we are blatantly disrespecting the dietary blueprint our ancestors left in our genes. Our meat-eating hunter-gatherer forebears never ate these carbs, and we plainly lack the metabolic oomph to deal with them now. This argument implies a fixed human nature – and a prehistoric past that dictates how we should eat today. But to what extent are modern humans really Pleistocene hominins under the skin? And what can these evolutionary arguments tell us, if anything, about the Western world’s ongoing health woes?

Read the whole article.

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Palaeolithic diet: Should we all eat like cavepeople?

Claudia Hammond
Medical Myths | 17 June 2014

(Science Photo Library)

We know modern convenience food can be unhealthy for us, but is reverting to a prehistoric diet the answer? Claudia Hammond examines the evidence.

They didn’t eat pizzas or curry. Not a single slice of cake would have passed their lips. They hunted animals for their meat, caught fish and collected nuts and berries from the forest. And according to some, these early Palaeolithic humans living between 2.5 million and 10,000 years ago had just the right diet for modern living.

The argument for the so-called “Palaeolithic diet” goes like this: the human body adapted to life during the Stone Age, and as our genetics has changed very little since then, this means biologically speaking we are far better-suited to the hunter-gatherers’ diet that existed before there was any agriculture. Details vary from diet to diet, but on the whole they advocate eschewing all dairy products, grain-based foods like pasta, bread or rice, and in some versions lentils and beans aren’t allowed. Proponents argue modern disorders like heart disease, diabetes and cancer have arisen primarily from the incompatibility between our current forms of diet and our prehistoric anatomy.

But what’s the evidence that eating like a caveman is better for us? There are two questions to answer here. First, is it true that we are biologically identical to Stone Age humans? And, second, does this mean we should we eat the same food – and is this diet healthier for us?

A diet of junk food isn't good for us, but is the answer to eat like our prehistoric ancestors did? (Getty Images)

Palaeolithic diet followers say that the reason we should follow this way of life is that this is the food our bodies and in particular, our digestive systems, have evolved to eat. It’s argued that consuming dairy products or anything unavailable before the advent of farming, is challenging both evolution and our bodies. A Polish study from 2012 estimates that in Western populations, at least 70% of daily energy intake comes from food that cavepeople would never or rarely have consumed including grains, dairy, refined sugars and processed fats.

Evolutionary biologists argue otherwise. Marlene Zuk at the University of Minnesota in the US, and author of the book Paleofantasy, says that because different genes change at different rates, there’s no reason to expect us to be genetically identical to people living in the Pleistocene. Evolution hasn’t occurred in this manner – we didn’t have the perfect human as an endpoint then and stop there. Humans have been constantly evolving. As she put it to me: “Some of those genes we had back in the Pleistocene were the same as the genes we had when life was aquatic, and no one’s suggesting we start filter feeding.”

One example of a relatively recent genetic change, and by recent I mean roughly 7,000 years ago, is lactase persistence. Babies survive on milk, but after weaning it used to be unusual for them to tolerate it and it would cause symptoms such as stomach pain and diarrhoea. Cattle began to be herded for their meat and skins, rather than for their milk. But the few who could digest dairy without discomfort, could drink the cow’s milk. This gave them an evolutionary advantage – here they not only had an extra source of food, but an uncontaminated drink. So they survived, passing on to their children the gene variant that tolerated milk. Soon more adults could drink milk, to differing extents in different places.

One example of how our genes have changed since prehistoric times is lactase persistence, which has allowed adults to tolerate milk. (Thinkstock)

Whether or not we are genetically identical to cavepeople, it is of course still possible that the Palaeolithic diet could be better for us. Few would argue that eating highly processed foods all the time is good, or that we wouldn’t benefit from eating some more fruit and vegetables. As details vary from diet to diet, this makes it a challenge when it comes to assessing them scientifically. That said, if a study were to compare a diet packed with junk food with the Palaeolithic diet you’d expect the Palaeolithic diet to come out on top. But what if you compared it with a healthy diet?

A few studies have done just that. They show that we do tend to lose weight faster on the Palaeolithic diet; however, the majority are very short-term, getting people to follow the diet for just three weeks or so, and with a very small number of participants. In one review of studies they list sample sizes of just 10, 29, 14 and 13 people. Persuading people to try the diet isn’t always easy. One study had to end early because for six months they were unable to recruit a single new participant.

Then earlier this year came headlines proclaiming that at last there was evidence that we should eat like Stone Age humans. The reason was that a long-term randomised controlled trial had been conducted. It only spanned two years, but this was long compared with the previous studies. The sample was also larger. Seventy obese post-menopausal women took part, with an average age of 60. For two years they were either given a Palaeolithic-type diet to follow or a low-fat Nordic diet, which didn’t exclude any foods, but had an emphasis on low-fat dairy products and high fibre foods such as wholegrain cereals. For each diet they were given targets on the ideal proportions of protein, fat and carbohydrate to eat.

Earlier this year we saw the biggest study exploring whether we should follow a diet like cavepeople (Science Photo Library)

What happened? Both groups lost weight, but after six months the women on the Palaeolithic diet had lost more, and their waists now measured less than those on the Nordic diet. It seemed as though this diet was better, but then things changed. After two years there was no difference in weight between the two groups. The only difference was in levels of the harmful blood fats, triglycerides, but even then they were at what would be considered safe, normal levels in the people on the Nordic diet too. Both groups found the diets difficult to manage and most people didn’t achieve the targets of eating the right amounts of each food group.

So, there’s no hard and fast evidence yet that we should be eating like cavepeople. It is of course unhealthy to eat a diet which mainly consists of highly processed foods like white bread and sugary cereals, but this doesn’t mean that all dairy products and grains need to be avoided unless you have a specific problem with them. In a three-week study from 2011 people found it hard to reach the recommended daily amounts of calcium, iron and fibre on the Palaeolithic diet. Not all studies are using exactly the same diet, though, which makes them hard to compare.

When it comes to losing weight, the advice is pretty dull – eat less and exercise more. Which is probably why any diet which claims to have found an alternative seems appealing, though. But, unfortunately, it seems that there’s still no magic bullet.

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New Research Supports Low-Carb Atkins Diet - Best Evidence So Far

An article in today's New York Times reports on new research around the issue of what type of diet is best for fat loss. The Journal of the American Medical Association published the results of a clinical trial by Dr. David Ludwig of Boston Children’s Hospital and his collaborators that showed a low-carb diet is better for those at risk of gaining fat - and it did so through a novel approach. But first some history.

For more than 50 years, various medical groups, as well as the government, have been pushing a low-fat diet for heart health and weight loss, a diet which ends up including more carbohydrates. The theory has always been that a calorie is calorie, or all calories are equal.

But this is a recent idea that began in the 1950s and 1960s - the article quotes a women's magazine from that era about how “Every woman knows that carbohydrate is fattening,” as two British dietitians began a 1963 British Journal of Nutrition article.

Dr. Atkins first began his research and publishing on the benefits of a low-carbohydrate diet in the early 1970s. His work is based on the knowledge that carbohydrates generate more insulin than either fat or protein, and insulin's function is to shuttle energy (glucose) - often in the form of triglycerides (an ester derived from glycerol and three fatty acid molecules) when the diet is high is sugars and starches - into muscle cells (following exercise or exertion) or into fat cells in the absence of glycogen depletion through physical exertion. 

The Atkins diet, based on studies of type-II diabetics, proposed that constant exposure to high insulin levels makes the body less sensitive to insulin, which requires more insulin, thus further decreasing insulin sensitivity. A diet based on fats and proteins supplies adequate energy (the liver can convert protein and fats into ketones for energy) and generates very little insulin secretion. Atkins found that doing a two-week period of almost zero carbohydrates can allow the body to become more sensitive to insulin. At this point, the diet reintroduces low-glycemic (producing low levels of blood sugar) carbohydrates (fibrous vegetables, some fruit, and beans) as the new normal diet pattern. It worked, but most doctors rejected his work until the late 1990s when other research (particularly that of Dr. Loren Cordain, author of The Paleo Diet) began to appear that supported his work.

This is context in which this new study appears.


Here is the main portion of the NYT article: What Really Makes Us Fat, By Gary Taubes

What was done by Dr. Ludwig’s team has never been done before. First they took obese subjects and effectively semi-starved them until they’d lost 10 to 15 percent of their weight. Such weight-reduced subjects are particularly susceptible to gaining the weight back. Their energy expenditure drops precipitously and they burn fewer calories than people who naturally weigh the same. This means they have to continually fight their hunger just to maintain their weight loss. The belief is that weight loss causes “metabolic adaptations,” which make it almost inevitable that the weight will return. Dr. Ludwig’s team then measured how many calories these weight-reduced subjects expended daily, and that’s how many they fed them. But now the subjects were rotated through three very different diets, one month for each. They ate the same amount of calories on all three, equal to what they were expending after their weight loss, but the nutrient composition of the diets was very different.

One diet was low-fat and thus high in carbohydrates. This was the diet we’re all advised to eat: whole grains, fruits, vegetables, lean sources of protein. One diet had a low glycemic index: fewer carbohydrates in total, and those that were included were slow to be digested — from beans, non-starchy vegetables and other minimally processed sources. The third diet was Atkins, which is very low in carbohydrates and high in fat and protein.

The results were remarkable. Put most simply, the fewer carbohydrates consumed, the more energy these weight-reduced people expended. On the very low-carbohydrate Atkins diet, there was virtually no metabolic adaptation to the weight loss. These subjects expended, on average, only 100 fewer calories a day than they did at their full weights. Eight of the 21 subjects expended more than they did at their full weights — the opposite of the predicted metabolic compensation.

On the very low-carbohydrate diet, Dr. Ludwig’s subjects expended 300 more calories a day than they did on the low-fat diet and 150 calories more than on the low-glycemic-index diet. As Dr. Ludwig explained, when the subjects were eating low-fat diets, they’d have to add an hour of moderate-intensity physical activity each day to expend as much energy as they would effortlessly on the very-low-carb diet. And this while consuming the same amount of calories. If the physical activity made them hungrier — a likely assumption — maintaining weight on the low-fat, high-carb diet would be even harder.  Why does this speak to the very cause of obesity? One way to think about this is to consider weight-reduced subjects as “pre-obese.” They’re almost assuredly going to get fatter, and so they can be research stand-ins — perhaps the best we have — for those of us who are merely predisposed to get fat but haven’t done so yet and might take a few years or decades longer to do it.

If we think of Dr. Ludwig’s subjects as pre-obese, then the study tells us that the nutrient composition of the diet can trigger the predisposition to get fat, independent of the calories consumed. The fewer carbohydrates we eat, the more easily we remain lean. The more carbohydrates, the more difficult. In other words, carbohydrates are fattening, and obesity is a fat-storage defect. What matters, then, is the quantity and quality of carbohydrates we consume and their effect on insulin.

From this perspective, the trial suggests that among the bad decisions we can make to maintain our weight is exactly what the government and medical organizations like the American Heart Association have been telling us to do: eat low-fat, carbohydrate-rich diets, even if those diets include whole grains and fruits and vegetables.

Research - Effect of Ketogenic Mediterranean diet with phytoextracts and low carbohydrates/high-protein meals on weight, cardiovascular risk factors, body composition and diet compliance

Excellent study that demonstrates both that very low-carb diets are quite healthy and that they can achieve high compliance. The outcomes on this study, after only 6 weeks, are quite good. A few tweaks would the results even better, but this is just a pilot study to look at brief outcomes and compliance.

From the open access Nutrition Journal.

Effect of Ketogenic Mediterranean diet with phytoextracts and low carbohydrates/high-protein meals on weight, cardiovascular risk factors, body composition and diet compliance in Italian council employees.

Antonio Paoli, Lorenzo Cenci and Keith A Grimaldi

Nutrition Journal 2011, 10:112 doi:10.1186/1475-2891-10-112

Published: 12 October 2011

Abstract (provisional)

Background

There has been increased interest in recent years in very low carbohydrate ketogenic diets (VLCKD) that, even though they are much discussed and often opposed, have undoubtedly been shown to be effective, at least in the short to medium term, as a tool to tackle obesity, hyperlipidemia and some cardiovascular risk factors. For this reason the ketogenic diet represents an interesting option but unfortunately suffers from a low compliance.. The aim of this pilot study is to ascertain the safety and effects of a modified ketogenic diet that utilizes ingredients which are low in carbohydrates but are formulated to simulate its aspect and taste and also contain phytoextracts to add beneficial effects of important vegetable components.

Methods

The study group consisted of 106 Rome council employees with a body mass index >25, age between 18 and 65 years (19 male and 87 female; mean age 48.49+/-10.3). We investigated the effects of a modified ketogenic diet based on green vegetables, olive oil, fish and meat plus dishes composed of high quality protein and virtually zero carbohydrate but which mimic their taste, with the addition of some herbal extracts (KEMEPHY ketogenic Mediterranean with phytoextracts). Calories in the diet were unlimited. Measurements were taken before and after 6 weeks of diet.

Results

There were no significant changes in BUN, ALT, AST, GGT and blood creatinine. We detected a significant (p<0.0001) reduction in BMI (31.45 Kg/m2 to 29.01 Kg/m2), body weight (86.15 kg to 79.43 Kg), percentage of fat mass (41.24 % to 34.99 %), waist circumference (106.56 cm to 97.10 cm), total cholesterol (204 mg/dl to 181 mg/dl), LDLc (150 mg/dl to 136 mg/dl), triglycerides (119 mg/dl to 93 mg/dl) and blood glucose (96 mg/dl to 91 mg/dl). There was a significant (p<0.0001) increase in HDLc (46 mg/dl to 52 mg/dl).

Conclusions

The KEMEPHY diet lead to weight reduction, improvements in cardiovascular risk markers, reduction in waist circumference and showed good compliance.

The complete article is available as a provisional PDF. The fully formatted PDF and HTML versions are in production.