We hear about new diets all the time and each sort of sounds good at the beginning but after a while most of them fall by the wayside. When scientific research supports a diet regimen, however, credence is given and we can look a little further.
A new study published in the Annals of Internal Medicine compared the weight loss of two groups, one on a low-fat diet (less than thirty percent of daily energy intake from total fat) and the other on a low-carbohydrate diet (less than forty grams per day).
First, the Conventional Wisdom
Back in the ’70s, a movement began to reduce the amount of fat in our diet, almost demonizing it. That’s not altogether unfounded, as trans fats (hydrogenated oils) are so bad for you as to be criminal, raising cholesterol to dangerous levels and resulting in cardiovascular disease. The processed food industry had started to boom right around then–no coincidence. The problem was, all fats were lumped together as being bad for you.
Get on the Wagon
In the ’80s, many people (like my mother) jumped on the no-fat bandwagon, thinking that would reduce her cholesterol and make her healthier. Her physician agreed with this plan. Sigh. She didn’t get healthier and her cholesterol levels didn’t change much after she switched to low-fat/no-fat margarine, “cheese”, mayonnaise, etc. And she didn’t FEEL better. But fat = bad, the doctor said so.
Then in the ’90s the Atkins diet was resurrected, a revolutionary change in diet philosophy that had been founded in 1972. This weight-loss plan became all the rage as it promoted a low-carbohydrate regime that disallowed whole grains, nuts, seeds, fruit, and legumes while allowing diet soda, hydrogenated vegetable oils, and dairy–and its own brand of processed food.
People started eating loads of meat to replace the pasta they had to sacrifice. Many experienced significant weight loss but found it difficult to maintain because we all love a crusty bread and a crisp apple. And the higher meat intake was wreaking its own health havoc.
The diet fell out of favor a while back because conventional wisdom hadn’t changed and the focus remained on a carbohydrate-rich diet that includes vast amounts of sugar, refined flours, salt, and processed food.
The rates of obesity continue to rise.
A decade later came the Paleolithic (“Paleo”) diet. Similar to the Atkins philosophy, Paleo stresses higher amounts of protein and healthy fats, with limited complex carbohydrates. The difference is that no processed food is allowed, strictly removing refined sugars and chemicals. The theory is this:
Our ancestors ate diets rich in protein and healthy fats with some complex carbohydrates mixed in. The pace of human genetic change in the industrial world has increased one hundred times faster in the last one hundred fifty years than it did in the previous six million; our bodies haven’t adapted which is why we get sick.
By returning to a species-appropriate diet, we can prevent and reverse inflammatory disease–which is responsible for the majority of disease-related illness and death in the U.S. Along with the foods of the diet are increases in physical activity and sleep and stress reduction–a more holistic approach.
Still, we Americans love our carbohydrates: bread, cereal, pasta, cookies, and other processed foods. Not to mention fast food. The problem with most of these is that many contain ingredients other than what is needed for a whole food, like preservatives, artificial colors and flavors, and loads of added sugar and salt. Over half of our daily calories come from wheat, sugar, and processed foods. The sacrifice is healthy proteins and fats.
Your body needs protein to build and maintain muscle and create healthy blood cells. It needs fats for brain function, cell communication, and nutrient absorption. Carbohydrates, when not burned as fuel, are stored as fat. Sugar makes you fat, not cholesterol.
And cancer literally lives on sugar.
The focus in the current study (back to that) was weight loss and risk for cardiovascular disease and diabetes. So here are the results: after twelve months, the group of subjects in the low-carbohydrate group had lost more weight in the form of fat mass and had achieved more balanced cholesterol levels than those in the low-fat diet group. Researchers concluded:
“The low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than the low-fat diet. Restricting carbohydrate may be an option for persons seeking to lose weight and reduce cardiovascular risk factors.”
The key is not only the volumes of nutrients but their sources; coconut and olive oils–while they may have higher fat content per se than vegetable oil (corn, canola, soy)–are nutritious fats that feed your cells and don’t tax them. Lean meats, fish, legumes, nuts, seeds, quinoa, and tempeh are all sources of good proteins.
Looks like we may have to cut down on the carbohydrates and stock up on the proteins and nutritious fats after all, if we want long-term weight loss: the new conventional wisdom?