Good piece at Runner’s World last week analyzed a large study on the effectiveness of low carb versus low fat diets. While the low carb group faired better, the actual takeaway from the study is far more subtle. My translation: the best diet for you is the one that addresses your own particular lifestyle and needs at any one give time. There is no magic bullet eating plan. We’re all different. We all do different things at different times the require a different set of nutritional strategy. Learning this is key to your longterm health and longevity. With that out of the way, let’s have a look at the article because it’s pretty interesting.
In a relatively large, randomized trial conducted at Tulane University, researchers put obese but healthy volunteers on a 12-month diet that was either “low fat” or “low carb.” The low-carb dieters lost an average of about 8 pounds more than the low-fat eaters, even though both started at about the same weight and consumed similar calories per day.
More surprisingly, the low-carb dieters enjoyed greater improvements in heart-health measures such as total cholesterol, HDL cholesterol, and c-reactive protein than the low-fat subjects. In other words, their relatively high consumption of fats (40.7 percent of all calories, including nearly double the saturated fat intake recommended by the American Heart Association) didn’t ruin their blood lipid profiles. To the contrary, the high-fat diet improved their blood fat levels, apparently turning upside down nearly 40 years of U.S. dietary recommendations about fat consumption and heart health.
While this sounds both damning to low fat dieters, as well as the AHA, it’s pretty simple to understand when we look at the reality of how we currently eat. We eat too many carbs. A crap-ton of them. And almost everyone who pays attention knows this. Processed foods, that are super high in simple carbs, are everywhere. Not just in what we eat. Drinks are the main culprit. Soda makes up somewhere between 10-20% of our caloric intake nationwide. That is unbelievable, making it almost impossible to eat a balanced diet given one statistic alone. And these statistics might not take into account coffee, tea, and energy drinks that often start out naked (coffee and tea have no calories) but are massive carb hits by the time we’ve decked them into frappucino territory. Anyway, we eat too much junk. Most of that junk is carbs.
On the fat note, it makes sense and it’s just a matter of time before the AHA comes around. We eat three things: proteins, fats, and carbs. Okay, alcohol, too, but for this argument we’ll toss it in with the carbs. Numerous and ever-more-detailed studies are showing us we can only consume and process a certain percentage of protein at a given time, so it’s limited. Carbs, as discussed, should be limited (btw, they still make up the bulk of our macronutrient ratio, it should just be closer to 40% than 80%, where it is for many people), and that leaves fat. Again, we’re awash in modern research showing that fat sources, especially from plants, almost cannot be over consumed. You can’t open a health magazine without being extolled the virtues of avocados, olives, seeds and nuts. Perhaps there’s some hyperbole at work but I challenge anyone to substitute all soda with plant fats and not see a massive improvement in their health. It’s nutrition at it’s most basic.
Overall, both groups did well. This shows that almost any regulation on how we generally eat works. This is true. We eat too much, and we eat far too much of things we don’t pay attention to. Simply noticing what you eat enough so that you can recall it by the end of the day is going to help most people improve their diets. One of our first pieces of nutritional advice is to journal what you eat. When people do this, we find they instantly eat better, even with no dietary guidance at all.
Things then turn more interesting.
Also, the trial showed no evidence of the glucose/insulin link proposed by Taubes and other diet writers as the mechanism behind the success of low-carb diets. Indeed, the low-fat/higher-carb eaters appeared to gain slightly more glucose/insulin control than the low-carb dieters.
So it’s tempting to say that the Tulane University trial burst two balloons at once: First, that high-fat diets are bad for heart health; and second that high-carb diets juice the glucose-insulin-fat deposition system.
Umm, yeah. Correctamundo. Diet book authors are beholden to find “facts” to support their plans beyond the standard “you eat terrible and this diet is healthy so you’re going to improve” line that is the essence of any actually-effective diet guide. But that doesn’t sound too convincing so, along with a bunch of recipes at stuff, authors provide all sorts of data that tries to show that whatever they’ve just learned is some kind of brand new secret we’ve never known before. To do this, they use science. Then they tend to misinterpret the beejesus out of it. My old pal Denis Faye has made ferreting out bogus research almost a religion. His blog is rife with it. If you’re interested, you should follow him and read everything he writes. It will definitely shed a light on what is actual science and not some sort of tidbit pulled from a quote based on a number that may or may not have been relevant to the study in the first place.
For those of us who’ve been looking at diet trends for ages, this isn’t strange at all. One of the things all longterm nutrition plans do is teach you your relationship with food. You don’t go into a diet thinking about it. It just happens. It isn’t rocket science, after all. It’s eating. There is nothing theoretical about it. When you eat differently your body reacts differently. When you perform better, you tend to begin to crave the things that enable your performance to improve. A book isn’t necessary. You will feel it. Over time, you’ll get better at interpreting it. And you will eat to adjust. Portion control is a massive topic in all dietary advice but it’s a very simple thing to control when you learn to read your body’s signals. When you base your food on performance, your body will tell you when its had enough food. And then you eat less. Therefore, we see this “strange” stat at the end of almost every long dietary study.
For runners who may want to try a lower-carb diet but still get sufficient high-octane fuel (the body “prefers” carbohydrates for high-intensity exercise like running), the best bet is probably to cut back carbs at all meals except the one before your running workout. Before a marathon, several days of carb-loading will likely pay off, but you don’t necessarily need high carbs all the time during your regular training.
Finally, we get the bingo moment. Eat for what you do. Carbohydrates are a fuel source. In any given period of time, the amount of fat and protein in your diet should remain relatively constant. Carbs should vary, specifically, based on what you do because you’re literally burn them during activity. When you only eat enough to use, they are magic. When you stuff yourself with them and sit around, they are poison. Unfortunately, we’ve become a country crazed on eating sports foods to fuel us for watching sports, and that is a very dangerous template. Simply reversing it, and saving your carbs for when you need them–and inserting more places in your life to burn them–is the one diet that I guarantee is going to work best for you. And you don’t need a study to tell you that.