Banting fat and fiction
• Many experts have weighed in on the pros and cons of this latest craze, but the bottom line is that a balanced diet of natural foods is the healthiest choice
Never has a nutritional debate featured so prominently in the media as during the past five years. Credit goes to the low-carbohydrate, high-fat craze known as “banting”, a variation on the discredited Atkins diet.
Critics say Banting pushers have “lost it”. Banting pushers lament that the critics “don’t get it”. And the media feasts on it.
A few prominent academics have thrown their weight behind the Banting message. The critics, brilliant academics of equal prominence, stand by their more balanced and conservative message. Both sides defend what they advocate. Both sides are concerned about the health of the population. Both can’t be right. Or can they?
The low-carbohydrate, highfat diet has been the topic of a vast amount of scientific research. The conclusion from the best minds in the field is that its justification all too often relies on cherry-picking, biased interpretation and wild extrapolation. That does not mean the message is entirely invalid.
There is indeed a place for a low-carbohydrate, high-fat diet. It is one of many weapons in the vast arsenal to fight obesity and diabetes — but it is certainly not a silver bullet.
Terminology is important: low-carbohydrate, high-fat can mean 45% fat, 43% carbohydrate and 12% protein (the Heart Foundation), or an extreme such as Banting: 66% fat, 8% carbohydrate and 26% protein. The carbohydrate component in Banting is so low that the body goes into ketosis — it burns mainly fat for fuel (hence the fat loss) instead of glucose.
Endocrinologists and dieticians have been prescribing low-carbohydrate, high-fat diets for decades for selected, morbidly obese patients, but rarely in the extreme Banting form because it is not without dangers. If you just want to lose 10kg or 20kg, there are safer, better, cheaper and far more sustainable ways to achieve that — such as proper eating habits.
The claims of Banting supporters sound impressive to lay people, but do not stand up to even superficial scrutiny by the better-informed.
Its supporters claim the diet is “cutting-edge” and that “if it were a drug, they would win a Nobel prize for it”. Yet they also reassuringly announce that it has been around since the 1800s (indeed it has — and it never worked).
William Banting, a wealthy 19th-century obese English undertaker, was put on a lowcarbohydrate, high-fat diet by his doctor. He lost some weight and in 1864 published a booklet about it, Letter on Corpulence.
It appears Banting had become obese from eating a diet high in calories and refined foods. When he stopped that and had a moderate intake of carbohydrates, fat and calories, he lost weight. Cutting-edge indeed.
The same thing happens today to most people on the Banting diet: they take a close and honest look at what they are eating, ditch the junk (overly processed food that contains a lot of refined carbohydrates and sugar) and eat less and healthier. If that is what Banting achieves, it can only be condoned.
However, real Banting is too extreme. One of the many problems is the drastic cut in fibre intake, causing serious constipation and poor gut health.
Eating is not just about macronutrients and calories. The calories do count, but do not count on counting them. What is more important is where those calories come from.
Eating a balance of natural foods in natural quantities restores the diversity of gut bacteria and decreases body-wide inflammatory responses to processed food and overeating. Gut bacteria and the inflammatory response are the vanguards of health and are influenced by what and how much is eaten.
GOOD CARBOHYDRATES
People on the Banting diet can be commended for their stance against sugar and refined carbohydrates (dieticians have advocated this forever).
But they throw away the baby with the bath water and vilify all carbohydrates.
Green peas are on their forbidden list, yet no one has become obese from eating them. There is nothing wrong with carbohydrates found in nature. Why would Mother Nature put so many great micronutrients, such as phytochemicals, minerals and vitamins, together with a poisonous macronutrient, carbohydrates?
Processed carbohydrates are marketed as healthy but are not. Breakfast cereals, for example, are so processed and far from their natural state that bodies regard them as junk food. Manufacturers claim they contain “added vitamins and fibre”, but why not leave in the vitamins and fibre in the first place?
Eat food from nature and not from a factory, and you’ll be fine. Eat a cob of corn for breakfast instead of what cereal manufacturers concoct with corn.
Eat artisanal bread, not industrial bread. Ignore the countless other carbohydrates sold in a box, bag or bottle.
The main axiom of people on low carbohydrate, high-fat diets is that carbohydrates set insulin free, and this hormone stores calories in fat tissue. So, they say, insulin makes you obese. Although that is true, it’s a colossal oversimplification.
To say we have insulin in our bodies to give us obesity is a bit like saying we have eyes to give us cataracts. Insulin is essential for survival. People can get obese from eating too much fat, but this does not involve insulin.
People on low-carbohydrate, high-fat diets claim carbohydrates lead to insulin resistance. This is also an oversimplification and rather illogical.
Why would we have a hormone that allows us to eat something, but when we eat that thing, we become resistant to that hormone?
Eating too many refined carbohydrates and sugar might indeed lead to insulin resistance (although never clearly proven in humans), obesity and cardiovascular disease, but it is very unlikely. The same is true for unprocessed, complex carbohydrates found in nature.
Rural South Africans who move to the cities change their diet from unprocessed to processed foods and their health suffers. Billions of rural Southeast Asians live on an 80% carbohydrate diet, yet there is a low prevalence of weight-related diseases. They eat small quantities of food at a time.
Insulin resistance is a defence mechanism against further weight gain: it’s the body locking the door to even more calorie storage when the larder is overflowing. Lose the weight and the insulin resistance has a very good chance of disappearing — a completely normal physiologic reaction.
Eating a very low-carbohydrate, Banting diet might actually increase insulin resistance and make diabetes worse. This is also a completely normal physiological reaction: glucose is the prime brain fuel and if there is very little of it available, the body is going to make sure the brain gets it and not other organs. It does that by making other organs insulin-resistant. Brain cells can take up glucose without the help of insulin, but most other organs can’t.
It’s all much more complicated than the Banting pushers want you to believe.
That’s why you should get individualised treatment from a dietician or a doctor, not follow sensational advice dished out on social media.
CAUSE AND CORRELATION
People on low-carbohydrate, high-fat diets keep committing the cardinal sin of confusing cause and correlation. They say their diet reverses diabetes or insulin resistance, improves hypertension and dyslipidemia (decreases cholesterol) and hence decreases the risk for heart disease.
That is all true, but the diet is not the cause. Weight loss is.
Because of the very highfat intake, dyslipidemia can worsen with Banting, even after weight loss.
These health improvements are also possible after losing weight on a diametrically opposite diet such as the Ornish diet, which is plant-based, high in healthy carbohydrates and low in fat. The improvements will follow if you lose weight for other reasons, such as contracting tuberculosis or becoming a cocaine addict.
People on the Banting diet claim that their diet is more effective than others for losing weight. That is true in some studies, not in all, and only in the short term. Most start regaining weight after a few months, and after one or two years, the weight loss is similar, irrespective of the diet.
For the vast majority of people, the low-carbohydrate, highfat diet is too extreme to continue for long.
People on the Banting diet insist that eating so much fat is safe, because there is no proof that fat causes anything.
The “long-term” studies they quote were conducted over two years or less. A human life is much longer than that. Smoking for two years and then stopping is unlikely to cause major harm in the long term. That does not mean smoking is safe.
A major study they refer to, involving almost 50,000 postmenopausal women and conducted over eight years, found that decreasing fat intake does not decrease the risk for cardiovascular disease.
However, the intervention group started out on a lower fat intake than the researchers initially anticipated and did not decrease their fat intake as much as the researchers had wanted. So they went from a low-ish fat diet to a low-fat one, but not a very low-fat diet.
It cannot be concluded that if they had doubled their fat intake (a low-carbohydrate, high-fat diet), their cardiovascular risk would not have increased. It’s like telling people who smoke three cigarettes a day to smoke just two a day for eight years, not finding a decrease in risk for lung cancer, and then concluding that smoking does not cause lung cancer.
Recently, a study conducted in rural Canada was published in the South African Medical Journal (SAMJ).
It was announced on the Banting website as a “game changer” — the irrefutable proof that a low-carbohydrate, highfat diet was safe and effective.
The study was refused by four other journals. This is not surprising since its quality is rather poor.
In essence, patients who wanted to lose weight were put on a very low-calorie diet, and when they achieved their goal weight, went onto a “high-fat” maintenance diet (what exactly was not specified).
The main author admits the paper was initially not designed as a study, that the data set was crude, that it was not recorded when the patients went from the weight-loss diet onto the maintenance diet and that measures were not standardised in time. This made analysing the data very complex and drawing inferences difficult.
The main author was not sure how food compliance was checked. The “high-fat” maintenance plan was not compared with anything else, which might well have shown better results.
Yet this “study” finds its way into the SAMJ.
Medical professionals strive to keep the population healthy. Unfortunately, there are no miracle cures and never will be.
The relentless and often derogatory charges from Banting fans that their critics are biased are unhelpful and unfair to brilliant scientists.
The South African dietary guidelines are the sum of the best available science and are updated on a regular basis. We all know what we should eat. We just don’t do it. Eat natural food in natural amounts. You’ll get very far with that.
EATING TOO MANY REFINED CARBOHYDRATES AND SUGAR MIGHT INDEED LEAD TO INSULIN RESISTANCE
THERE IS INDEED A PLACE FOR A LOWCARBOHYDRATE, HIGH-FAT DIET … BUT IT IS NOT A SILVER BULLET