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The Facts about Fat

[Previously published in Longevity magazine print edition.]

Prepare to turn Conventional Wisdom on its head. What you thought you knew about fat, cholesterol and healthy eating might not be quite so accurate after all.

We all know that to lose weight and increase health, the average person should eat less and exercise more, right? In the calories-in, calories-out equation, it’s a matter of getting in fewer than we expend. And it’s pretty obvious that if we want to lose fat – whether for better looks or heart health – we shouldn’t be taking it in, right?

Ummm… No.

Though our logic insists that these are irrefutable facts, the research does not actually back them up. Now a number of scientists are explaining why. And the implications for you and me are fairly radical.

“The Elusive Benefits of Undereating.” That’s the name of one of the chapters in science writer Gary Taubes’ book Why we get Fat (published by Alfred A Knopf) and it makes for pretty depressing reading if you’ve spent years trying to eat less in order to lose weight. Amongst a myriad other studies Taubes cites is a collection of Women’s Health Initiative studies in the early 1990s in which 20 000 obese and overweight women were put on a low-fat diet for eight years but lost an average only about a kilogram each – despite reducing their intake by an average of 360 calories per day for all of those years! And, to add insult to injury, their waist measurements increased.

Taubes notes that “This wasn’t the only disappointing result in the study. The WHI investigators also reported that the low-fat diet failed to prevent heart disease, cancer or anything else.”

These studies do not stand in isolation. Quite astoundingly, no scientific study has ever conclusively proved that eating less or exercising more will result in sustained weight loss. In 2007 even the American Heart Association had to admit that the notion is only a rational but unproved hypothesis. “It is reasonable to assume that persons with relatively high energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures… So far data to support this hypothesis are not particularly compelling.”

Taubes argues that the evidence to support our logic is backward: we don’t get fat and develop heart disease because we are slothful and gluttonous. Rather we exercise too little and eat too much because we get fat. In the same way a teenager eats more because they’re going through a growth spurt, rather than going through that adolescent growth spurt because they start eating more. Make sense?

Okay, so if it’s not overeating that’s making us fat and unhealthy, then what is? The answer is simple (and also very rational): it’s not HOW MUCH we eat but WHAT we eat. And what we should not be eating, according to a host of scientists whose studies can now no longer be ignored, is carbohydrate.

Professor Tim Noakes, Discovery Health Professor of Exercise and Sports Science at UCT, uses strong words when explaining the issue. He goes so far as to call carbs ““toxic”. And he uses words like “malpractice” for the way the medical fraternity has been giving scientifically uncorroborated advice to diabetics.

At the heart of it all is insulin. Diabetics are told to inject it. Taubes and Noakes and the like are saying get rid of it.

Simply put, it’s carbs that cause your insulin to spike. And insulin directs two significant enzymes. Hormone-sensitive lipase (HSL) works inside the fat cells to break down triglycerides into their component fatty acids, which can then escape into the circulation. Lipoprotein lipase (LPL) has the opposite effect: it pulls fat out of the bloodstream and into the cells.

Your body begins secreting insulin as you even start thinking about eating a carbohydrate meal. The insulin signals the fat cells to shut down the release of fatty acids and instead to start taking them up (via LPL) from the circulation. You get hungrier, begin eating and secrete more insulin. The carbohydrates are digested and enter the circulation as glucose, causing blood sugar levels to rise, and so your body responds by secreting still more insulin. Fat you are eating is stored as triglycerides in the fat cells, as are some of the carbohydrates that are converted into fat in the liver. In other words: the fat cells get fatter. This fat stays in the fat cells until the insulin levels drop.

“The one thing we absolutely have to do if we want to get leaner – if we want to get fat out of our fat tissue and burn it – is to lower our insulin levels and to secrete less insulin to begin with, ” summarises Taubes.

You might have heard the term “paleo diet”. This is not a specific diet per se, but it’s the notion that we are best off emulating the eating of our ancestors. After all, they lived as hunter-gatherers for two million years, whereas the refined carbohydrates and sweetened fruits so prevalent now have only been around for half a century. Noakes believes that, for the about 60% of the population that he reckons is sensitive to or intolerant of carbs, it’s safest to return to the food our bodies have long been attuned to.

He points out that even the carbohydrates that our forefathers ate were very “poor” – more roughage than anything else – rather than the very concentrated amounts that come in even one kernal of today’s mielie. Even the fruits we eat today are vastly different from those our ancestors enjoyed. And they certainly weren’t available all year round. Today’s fruit is bred to be juicier and sweeter.

“The evidence is so clear that the weight gain in the US has accelerated since ‘91, which is when diet guidelines came out promoting less fat. The fact there so little research is being done suggests the industry wants Americans to get fat and so use their drugs. Clearly it’s an orchestrated response which is devoid of fact,” says Noakes. Those are very strong words, of course. But consider the amount of money at stake: One drug alone, Pfizer’s Lipitor, brings in as much as US$13 billion for the company per year.

“The evidence that we have is that the high carb diet is killing people,” he says. “The root of the sicknesses most prevalent in the First World today – diabetes, hypertension, hypercholesterol, obesity – is carbohydrate intolerance, which is firstly managed by reducing carb intake. If I was in medical practice and treating diabetics, I would immediately take them off all carbohydrates.”

Okay, so that’s the story on eating less carbs. But surely we shouldn’t be eating more fat, as the paleo diet suggests we should? Mark Sisson, author of The Primal Blueprint, argues that the “eating fat drives cholesterol drives heart disease” paradigm is very narrow and outdated. He argues that the cause of heart disease is “inflammation and oxidation, driven primarily by poor food choices, excessive insulin production and all forms of stress in excess, including overexercising”.

Sisson cites the Framingham Heart Study, which has followed the dietary habits of 15 000 participants (the residents of the town of that name in Massachusetts, USA) for three generations. It is, he says, widely regarded as the longest (been going since 1948), most comprehensive study of health and illness factors on a population in medical history. According to the study’s director, Dr William Castelli, the results are clear: “Serum cholesterol is not a strong risk factor for coronary heart disease.”

Sisson points out the study’s highlight that “there is no correlation between dietary cholesterol intake and blood cholesterol levels.” Additionally “Framingham residents who ate the most cholesterol, saturated fat, and total calories actually weighed the least and were the most physically active.”

And Noakes? By following the paleo diet, he’s not only lost 15kg in seven months after years and years of struggling to lose weight despite the countless marathons and ultras he’s been participating in. But at 62 he’s also running faster and stronger than ever before, and recovering more quickly. He is most delighted with the results of his “experiment of one”.

The “No Sugar, No Starch” Diet

Low-carb diets are, of course, nothing new. Like Atkins some years back; the French Dukan Diet has been making headlines, especially since it helped Kate Middleton lose so much (too much, actually) weight for her wedding. The difference now is that in years gone by, these were seen as fad diets, now scientific evidence is suggesting they had merit all along. The guidelines below are from those prescribed by the Lifestyle Medicine Clinic at Duke University Medical Center, and quoted in full in Why we get Fat.

For most effective weight loss, you need to keep the total number of carbohydrate grams to fewer than 20g per day.

Quantities: eat when you are hungry; stop when you are full.

When you are hungry, eat freely from the following:

Meat, poultry, fish and shellfish, whole eggs. Without restriction and you do not have to avoid the natural fat that comes with these foods.

Foods that must be eaten every day:

  • Salad greens: 2 cups a day
  • Vegetables: 1 cup (measured uncooked) a day
  • Bouillon (2 cups a day, needed for sodium replenishment) Clear broth consommé unless you are on a sodium restricted diet for hypertension or heart failure.

Foods allowed in limited quantities:

  • Cheese
  • Cream
  • Mayonnaise
  • Olives
  • Lemon/lime juice
  • Soy sauces
  • Pickles
  • Meat snacks such as slices of ham, salami or turkey.

Foods to avoid:

  • Sugars such as white and brown sugar, syrup, honey, beer, milk, flavoured yoghurts, fruit juice, fruit.
  • Starches such as grains, rice, cereals, flour, cornstarch, pasta, bread, and “starchy” vegetables such as carrots, corn, peas, potatoes and parsnips.
  • Margarine and hydrogenated oils.


  • The best beverage is water. Drink as much as you would like, including essence-flavoured seltzers.
  • You may have up to three cups of black coffee, tea or caffeinated diet soda per day.
  • At first avoid all alcohol, but later moderate quantities, if low in carbohydrates, can be added.

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