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“Spiders spin webs because they are spiders, and we humans eat the way we do and like the foods we do because we’re humans.” Susan B. Roberts, PhD, The Instinct Diet (Workman, 2008)
Calories Matter, But Instinctive Behavior Matters More
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Carbs also Matter—to the Brain
You probably heard about the new finding that equal-calorie diets with different amounts of carbohydrate, fat, and protein (high, low, or moderate) caused essentially the same weight loss. All that matters, it seems, is calories in and calories out. Macro-nutrient composition doesn’t make any difference. You may not have heard, however, that weight loss from all diet combinations stopped after six months; at two years the dieters had regained half the loss and were on the way to regaining the entire loss. All of the dietary mixes are apparently failing.
Let’s look at the new study, and then talk about an approach that does work.
The study is reported in the New England Journal of Medicine (2/26/2009). You can read it free online: http://content.nejm.org/cgi/content/full/360/9/859
More than 800 overweight adults volunteered for one of four eating plans roughly equivalent to popular diets such as Atkins (low carbs), Ornish (low fat), Mediterranean (moderate fat, mostly vegetarian) and Zone (40-30-30). All diets included the same heart-healthy foods, but in different proportions. To minimize the effect of outside influences, the researchers avoided direct reproduction of the popular diets; for example, none of the diets were higher than 40% fat, or lower in carbohydrate and protein than 35% and 15%, respectively. All participants were advised to exercise at a moderate level 90 minutes a week. Each plan was designed to create a 750 calorie deficit each day. The study ran for two years, unusually long for an intervention study. All participants were offered regular diet counseling.
Results were essentially the same for all four diet groups. Reported satiety, hunger, and satisfaction were also similar.
Participants lost an average of 13 pounds at six months, but began regaining weight after one year. At two years, the average loss was down to about nine pounds and two inches around the waist. Many had returned to their former eating habits. The participants apparently couldn’t stick to any of the diet plans.
In an accompanying editorial, Martijn B. Katan, PhD, stressed that the subjects had difficulty adhering to the assigned ratios. “Protein intake was intended to differ by 10%,” Katan wrote, “but the actual difference as assessed by measurement of urinary nitrogen excretion, was 1 to 2%.” In addition, he says, objective measurements showed that carbohydrate and fat intake goals were not achieved.
It is helpful to know that calorie-count is what matters. But what difference does it make if people can’t, or won’t, stick to calorie (or macro-nutrient) goals? For all intents and purposes, we are back to square one.
“Even these highly motivated, intelligent participants who were coached by expert professionals could not achieve the weight loss needed to reverse the obesity epidemic,” Dr. Katan of Amsterdam’s Free University was forced to conclude. (Those who attended counseling sessions regularly throughout the study were significantly more likely to lose weight.)
“The effect of any particular diet group was minuscule, but the effect of individual behavior is humongous,” said Frank M. Sacks, MD, lead author of the study and professor of cardiovascular disease prevention at Harvard School of Public Health. “We had some people losing 50 pounds, and some people gaining 5 pounds. That’s what we don’t have a clue about. I think in the future, researchers should focus…on finding what is really the biggest governor of success in these individuals.”
Let’s look at the work of Susan B. Roberts, PhD, professor of nutrition and psychiatry at Tufts University, who has studied basic food instincts which control how we eat. The answer, says Roberts, lies in managing the controls. Her book, The Instinct Diet (Workman, 2008) tells you how to control the controls. (Hint: You don’t have to suffer to lose weight and keep it off. Being hungry and feeling deprived are not part of the deal.)
The Five Food Instincts
Dr Roberts has been studying the science of nutrition and weight loss for 20 years—she has run a research laboratory at Tufts University in Boston for 17 of those years—and has found “striking agreement” that five things affect our eating behavior: “hunger, the availability of food, the variety of food, the familiarity of food, and how rich or calorie-dense the food is.”
“We cannot [override] these instincts,” she says. But once we understand the signals that trigger them, “we can get our food instincts to work for us, not against us, in the battle against excess weight.”
Let’s look at how they work one by one—and how we can work with them.
HUNGER: The solution is to acknowledge—and accept—that we need to “satisfy” our hunger. Stop fighting it. “We like feeling full,” says Roberts.
We know from the new study that there is no magic macronutrient balance. High or low carb, or fat, or protein doesn’t make it easier to control calorie intake. So what is the answer?
“Controlling the signals received by our food brain from our body and sensory centers is the key to getting all our food instincts, including hunger, working for us,” says Roberts. There is more than one way to signal our brain that we’ve had enough to eat, without overshooting our calorie needs.
“There are four effective ways to accomplish this,” says Roberts: high-fiber, high-protein, low-Glycemic Index, and volume. She recommends using them all; that's important, you'll need all four methods to stay satisfied.
It’s well-known that fiber in the diet makes you feel full; see http://www.cbass.com/fiber.htm Roberts recommends including high fiber foods (grains, cereal, beans, vegetables, fruits) in most meals. “Do be sure to drink six to eight glasses of water daily when you eat more fiber,” she counsels, “to get the full benefits and prevent constipation.” It’s the water-holding property that makes fiber so filling. (Water, of course, takes up space but contains no calories.)
Foods high in protein, such as fish or chicken, are also very satisfying, and slow the return of hunger. They are digested slowly and don’t cause large fluctuations in blood sugar. Unlike many carbohydrate sources, protein foods are digested over hours rather than minutes. Roberts suggests combining fish or chicken with green vegetables or salad. “The trouble with high-protein diets,” she warns, “is that they can get really boring…The temptation to cheat may get stronger and stronger.”
That’s why she suggests making high-protein one of many options. “You can go to a restaurant and have half a lean entrée with a side salad and a glass of mineral water and keep your diet without making a public fuss about it.” (Carol and I frequently enjoy this option when eating out, but we usually have salad and vegetables.)
Low-glycemic foods, which cause only a small rise in blood sugar, are another good option for controlling how much we eat. “Low-GI foods have been shown to suppress hunger extremely well,” Roberts explains, “because the more stable blood glucose produced by these foods tells our food brain that all is well and we don’t need to eat again yet.”
The problem is that GI values can be confusing; see http://www.cbass.com/GlycemicIndex.htm
Don’t worry, says Roberts. “Here’s how to think about it: Unrefined, whole, chunky, lightly cooked and sour foods almost always have the low GIs.”
Another alternative (which is suggested in Challenge Yourself) is combining low-GI foods with high-GI foods for taste. Roberts says, “Low-GI foods, when eaten alone, may not taste as good as foods with higher GI values. They’re digested more slowly, so our brain learns to like them but not love them, probably because they don’t release as many of the feel-good taste and reward chemicals.”
A steady diet of low-GI foods will “tempt you to cheat,” Roberts warns. “We…seem to instinctively crave carbohydrates, and any plan that doesn’t have a way to give you some carbs in a healthy form will be fundamentally unsatisfying after a while.” (More about the need for carbs below)
The fourth and last way to deal with hunger is “volume.” Pioneered by Volumetrics author Barbara Rolls http://www.cbass.com/volumetrics.htm , this method of controlling hunger relies on the fact that volume trumps calories in making us feel full. “The mechanism isn’t known for sure,” says Roberts, “but is probably related to the activation of stretch receptors in the stomach or simply our perception of the right amount of food. As long as food is bulky, it doesn’t matter as much where the majority of calories come from.”
Good high-volume options, according to Dr. Roberts, are high-fiber cereal with low-fat milk, soup with dense particles to slow down digestion, and large dinner-size salads with something substantial on top, such as grilled chicken breast, seeds, or nuts. Something chewy is good, because chewing helps to make you feel full and satisfied.
Remember, don’t pick one or two ways to cope with the hunger instinct, use all four (fiber, protein, low-GI, and volume) to make sure every meal or snack makes you feel full and satisfied—without giving you too many calories.
I’ve given lots of details on managing the hunger instinct, because it is clearly the basic food instinct. Dealing with it puts us well on the way to controlling the other four instincts, which we’ll cover briefly.
AVAILABILITY: This one is pretty straightforward. If food is there, we’re programmed to eat it. It’s the basis for my practice of putting on the table only the food I plan to eat. If I want more, I get up and get it—but I stop and think about it first. I almost always decide I’ve had all I really want. That simple rule has saved me from eating many thousands of excess calories.
Dr. Roberts explains that this instinct came into being thousands of years ago. “This was essential for survival, and the most successful survivors were those who ate whenever food was available.”
“So it’s up to you to avoid temptation by getting rid of what tempts you,” says Roberts. It’s as simple as that. Get the bad stuff out of your home—and don’t buy more. If you really crave an ice cream sundae or a deep dish pizza, go out and have it. Just don’t make a habit of it.
See also mindless eating: http://www.cbass.com/MindlessEating.htm
CALORIE DENSITY: Those who have read my first book Ripped will remember my cardinal rule: “Avoid concentrated calories.” I discovered that by eating only whole, unprocessed foods, you avoid almost all concentrated calorie foods, and you won’t overeat.
That’s still my rule.
“Almost everybody loves high-calorie foods, but does this mean we’re instinctively attracted to foods that are jam-packed with calories?” Roberts asks rhetorically. “You bet it does,” she states unequivocally.
Again, it goes back to ancient times, according to Dr. Roberts. “An affinity for foods loaded with calories was an asset during early human development, when the next meal was an unpredictable event,” she explains. “The more calories per ounce a food has, the more we prefer it.”
Macronutrients don’t seem to matter, says Roberts. “In fact, the most popular foods are actually a mixture of [carbs, fat and protein]…Our strongest preferences are for foods containing some of those rapidly digested white carbs, with a little fat and protein thrown in for good measure.”
Attempting to avoid calorie dense food altogether is not a good idea, however. It won’t work. The key is to recognize the danger and be careful not to overdo. As noted, I eat mainly whole, unprocessed foods—and only have an occasional sweet treat.
An occasional splurge can actually be beneficial, because it gets the craving out of your system, allowing you to happily go back to healthy eating most of the time. It works for me on major holidays. I eat my fill, and then go back to normal eating the next day. The second part is the key, of course.
You’ll find other good suggests for avoiding calorie-dense foods in Dr. Roberts’ book.
FAMILIARITY: My practice of eating frequent meals and snacks to stay ahead of the hunger curve—and in control—dovetails with this instinct. I could just as easily make a habit of skipping breakfast, snacking haphazardly during the day, and stuffing myself in the evening—but it wouldn’t help me control how much I eat.
The same is true of the kind of food we usually eat. You can make a habit of eating healthy meals, or Coke, burgers and fries.
“We love what we know,” Roberts writes. “People enjoy eating food that’s familiar to them.”
“Instinctively, we’re drawn to what we know,” she explains. “Historically, this instinct kept us safe. For our Paleolithic ancestors, being cautious about trying new foods was all that stood between a good dinner and death by poison.”
You can change, however. Start eating healthy, regular meals and pretty soon you’ll get used to it—and actually prefer eating that way.
“Learn to love what’s good for you,” Roberts suggests. “Repetition is all it takes.” Try it. You’ll like it.
To learn more about this instinct and how to make it work for you, read Dr. Roberts’ book.
VARIETY: We are programmed to eat a widely. Again, it was a matter of survival. “Because no single food has all the nutrients that humans need, it was essential for them to eat a wide variety of foods in order to get the healthy nutrition that would keep them alive,” Roberts explains. “Variety instinctively felt right.”
Like the other food instincts, this one can work for or against us.
Too much variety leads to over eating. “Even fish and other wild creatures eat more food when they’re presented with more variety,” Roberts tells us. “In study after study, variety has been shown to have a huge effect on the amount of food we eat.”
This instinct is closely related to the “availability” instinct. The difference is that availability relates to amount, and variety relates to, well, variety. The key is to understand that both instincts are in play.
Not surprisingly, the fixes are much the same. Variety can be good if it’s the right kind. Roberts and her colleagues at the Tufts lab “discovered that eating a wide variety of high calorie foods…leads to weight gain. Conversely, eating a greater variety of vegetables can double or triple total vegetable consumption, which in turn reduces overall calorie intake.”
So the answer to both instincts is to replace the bad stuff with the good stuff. A wide variety of junk food is likely to make you fat, but a house with lots of fruits, vegetables, whole grains, beans, fish, seeds, and nuts will help you become and stay lean.
You can take it from there.
You’ll find many more motivational and behavioral tips, along with a three-stage program with menus for omnivores and vegetarians, in Roberts’ new book, The Instinct Diet.
Take it from Dr. Roberts—and me—managing your food instincts is far more important than calorie counting or whether you eat a low-fat or a low-carb diet.
Before wrapping our discussion, we promised to talk about the need for carbs. I want to briefly tell you about an up-to-the-minute study spotlighting a danger inherent in low-carb eating.
Cut Carbs, Starve Your Brain
In Ripped, I told about an episode where cutting carbs to practically zero left me so tired that I couldn’t think straight. Eating two nectarines brought me out of the stupor; it literally made me feel “like a new person.” Interestingly, I didn’t remember the details until Carol filled me in while I was writing Ripped. Except for feeling very tired, I apparently thought I was doing okay. About all I remembered clearly was being miraculously revived after eating the nectarines.
My explanation after gathering all the facts: “The carbohydrates in the nectarines were easily converted to the glucose (blood sugar) that my brain required to function properly.” A study by researchers at Tufts University (Appetite, February 2009) suggests a more complete—and interesting—analysis.
The researchers compared 19 women who were allowed to choose a low-carb diet (similar to Atkins) or a reduced-calorie balanced diet recommended by the American Dietetic Association (ADA). Nine of the women selected the Atkins-style diet and 10 chose the ADA diet. The low-carb group was instructed to cut carbs completely for the first week, add 5-8 grams per day in week two, and an additional 5-8 g in the third week (total 10-16 g of carbs per day). The ADA group was advised to calculate their calorie intake based on their bodyweight, while conforming to the recommended daily allowance for carbs: 130 grams, based in part on what the brain needs for food.
All of the women were tested using a battery of assessments for cognitive function (confusion, memory, attention, and others) 72 hours before starting the diets, and again 48 hours and one, two, and three weeks after going on the diets. They were then retested two and three weeks after carbohydrates were reintroduced to the low-carb dieters.
The Tufts researchers “proposed that dietary carbohydrate restriction would impair cognitive performance in the early phases of the diet, and that this impairment would be [reversed] by reintroduction of carbohydrate.”
As background, the researchers explained that the brain’s primary fuel is glucose, which isn’t stored in the brain, and must be supplied from limited amounts of glycogen stored in the liver and muscle tissue—and carbohydrates in the diet. Importantly, glucose can not be metabolized from fat.
“The body will consume its glycogen stores in a matter of 1-2 days,” the scientists explained. Earlier research on epilepsy sufferers and animals, they added, suggests that carbohydrate restriction “can profoundly influence brain functioning.”
“Although the study had a modest sample size, the results showed a clear difference in cognitive performance as a function of diet,” Holly A. Taylor, PhD, corresponding author of the study, is quoted as saying in Tufts Health & Nutrition Letter.
The details, as revealed in the report, are very interesting.
Confusion ratings were a mixed bag. The low-carb group reported somewhat more confusion at 48 hours and 3 weeks, but the ADA dieters were significantly more confused during the middle portion of the study, at 1 week and 2 weeks. (Calorie restriction is not without consequences.) Consistent with previous studies, the low-carb dieters outperformed the ADA group in attention tests. (Protein produces alertness, carbohydrates less tension/more calmness.) On all other measures, however, the ADA group outperformed. Those on the low-carb diet suffered a gradual decrease in memory performance and scored slower reaction times on all tests.
Happily, cognitive function was restored after the low-carb dieters resumed eating carbs.
The researchers concluded: “The current study suggests that the macronutrient makeup of various weight-loss regimens are likely to have both positive and negative effects on our ability to think, attend, and remember.”
Sounds like a balanced diet, with ample carbs and protein, would be the best bet.
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These findings seem to explain with my low-carb blackout. My analysis in Ripped was right on, as far as it went. My brain was showing all the signs of carb starvation.
Pass the carbs. Fruit, please.
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