Fat Chance: Why Diet Advice Seems to Keep Changing

Butter is back, pasta is passé and you don’t need all that fruit & veg after all? Haaretz tries to make order of the latest dietary bombshell, courtesy of the Lancet

Shoppers at a fruit and vegetable stall in eastern England, August 29, 2017.
Shoppers browsing at a fruit and vegetable stall in eastern England. But should they be aiming for five a day, 10 a day or less? Good question. Chris Ratcliffe/Bloomberg

Carbohydrates are out, fat is in and fresh fruit and vegetables have lost some of their luster, after a vast global study published in the Lancet last week concluded that present dietary guidelines to maintain cardiovascular health are askew.

When the gigantic study group of over 130,000 people was divided into five groups based on fat consumption, the group eating the most fat – of any origin! – were 23 percent less likely to die during the study than those who ate the least. Animal, vegetable – didn’t matter, fat improved survival.

Fats (although not trans fats) were not significantly associated with risk of heart attack, the new study found.

It had bad news for pasta lovers, though. A higher carbohydrate intake was associated with higher risk of total mortality.

Again separating the vast study group into five groups based on carbohydrate habits, those who ate the most carbs were 28 percent more likely to die from any cause during the study than those who ate the least.

Why do dietary recommendations keep changing? Why do the health authorities keep “getting it wrong”? Who should we believe?

Diet recommendations change because of new information. Leaving political agendas aside, if the health authorities “get it wrong,” it’s usually because of partial information or parameters left out. When new information comes in, the conclusions are updated.

So it’s not that the health authorities keep getting it wrong; it’s that the process of formulating dietary recommendations is ridiculously hard. There are an insanely high number of parameters, and more information gets added every day.

Strands of spaghetti at the Barilla pasta plant in Parma, Italy.
Bloomberg

In any case, the bottom line of last week’s study showing that fat is good and carbohydrates are bad is EXACTLY the same as in every other dietary study not done by people wearing tinfoil hats: what really matters is moderation.

“Our study showed that the nature of association between nutrients and health outcomes are more complex than previously assumed and it depends on the amount of nutrient consumed,” lead author Dr. Mahshid Dehghan of McMaster University explained to Haaretz. “If total fat and major types (saturated and unsaturated fats) are consumed in moderation, no adverse consequences will be expected,” she said.

Coffee had also been in the doghouse for decades, but today the pendulum has swung in its favor, by and large, based on the latest information. And don’t even ask about chocolate and red wine.

Who should we believe? Our own common sense, while doing our best not to cherry-pick information. We should reach our own conclusions, based on the state of our health, family history of intolerances and factor in all the information in our possession, not some of it. Good luck with that.

Hold that apple

The latest nutritional bombshell – fat good, carbs bad – arrived courtesy of the Lancet, which studied correlations between diet and cardiovascular disease.

During the test period (2003 to 2013), nearly 5,800 of the test subjects died and 4,800 had cardiovascular trouble – meaning anything from coronaries to strokes.

To live longer, people should eat more fat than currently recommended, and derive less of their energy from carbohydrates than is currently recommended, says the paper. The findings apply to the general population without history of cardiovascular disease, the authors explain.

Nor do people have to eat five portions of fruit and vegetables (or legumes) daily, as the World Health Organization recommends. Three to four will do, according to the Lancet.

You can gorge on fruit and vegetables until the cows come home. But the added value beyond three or four portions seems to be negligible. So if fruit & vegetables are costly in your area and/or you just don’t like them, you can scale back – a little.

Just this February, the press was reporting – based on a different major study, encompassing two million people – that if five portions of fruit and vegetables is good, 10 is better.

In fact, the two studies are not incompatible. “Serving sizes must be considered when comparing the results,” co-author Victoria Miller of McMaster University told Haaretz. Once serving sizes are adjusted, the two studies are compatible.

“We found that higher fruit, vegetable and legume intake is associated with a lower risk of total mortality,” Miller elaborated. “Our findings show the lowest risk of death in those who consume three to four servings of fruit, vegetables and legumes per day (equivalent to 375 to 500 grams), with little additional benefit for intake beyond that range.”

Our friend butter

Presently, the WHO recommends that people derive 30 percent of their energy needs from fat. It also urges avoiding the kind of saturated fats found in meat and dairy. One recommendation seems low, the second misguided. How were the “wrong” recommendations reached, and how did they remain in place for so long?

“The guidelines were developed some four decades back, mainly using data from some European countries (such as Finland) where fat and saturated fat intakes were very high – for instance, total fat intake was greater than 40 percent of caloric intake and saturated fats was greater than 20 percent of caloric intake,” explains Dehghan. “It is not clear whether the harm seen at such high levels applies to current global intakes, or countries outside of North America and Europe where fat intakes are much lower.

“Also, for decades, dietary guidelines have largely focused on reducing total fat and saturated fat intake based on the idea that reducing fat consumption should reduce the risk of cardiovascular disease,” she continues. “But this did not take into account what nutrients replace saturated fats in the diet.”

Since carbs are cheap, they came to replace fats – especially saturated fat, Dehghan says. That has turned out to be a bad idea.

Anyway, saturated fats are found in animal products and dairy. The new science says they’re safe to eat (cardiovascularly speaking).

Unsaturated fats derive from plants and fish. They are also fine to eat.

Trans fats (sometimes nicknamed hydrogenated oil) are made by industry from certain unsaturated fats. They are used to extend the shelf life of industrial foods, like margarine, bourekas and cookies. They are not considered fine to eat.

The new study recommends both saturated and unsaturated fats as lowering the total mortality risk but not trans fat, says the paper. They didn’t study trans fats, says Dehghan, adding, “The harm of trans fat has been shown by many studies.”

Why had scientists reached other recommendations? Again, it’s all about parameters and environments. For one thing, the guidelines were based on a skewed data base. “Most available data are from European and North American populations where nutrition excess is more likely, so their applicability to other populations is unclear,” they drily write in the Lancet.