Will eating high-glycemic foods cause you to gain weight or develop health problems? Despite the concerns evoked when one considers their actions in the body—and the media hype—there is very little consistency in the epidemiologic research that examines the association between high-glycemic eating habits and increased risk for diabetes, cardiovascular disease, or weight gain.
139
The ambiguity in the research probably reflects the limits of scientific reductionism: that overall dietary patterns play a much larger role in weight and health and the impact of individual nutrients is only apparent when part of a larger trend. In other words, you may be able to get away with a high-glycemic eating style if your other dietary choices support good health.
The difficulty with a high-glycemic eating habit may have more to do with what it’s missing than what it contains: fiber. Fiber plays a large role in how your body handles other carbohydrates. It acts as a dense filter, slowing the rate at which other carbohydrates are digested in much the same way a sand bag slows the rate at which rainwater enters the ground. This filtering, in turn, results in a slow, steady release of insulin, instead of that abrupt spike. Fiber also provides a sustained feeling of fullness, magnified by the water it absorbs. In fact, foods high in fiber will make you feel fuller than the same amount (or more) of any other kind of food.
140
Yet less than one of the 10.6 servings of grain products we eat in an average day is made up of fiber-rich whole grains.
136
And the typical American diet contains
two to three times
less fiber than that of our (thin) Paleolithic ancestors.
141
In the studies that suggest high-glycemic foods increase diabetes risk, that risk disappears when the diet is otherwise rich in fiber.
142
143
144
145
146
Fiber-rich foods include whole, unprocessed vegetables, grains, beans, fruits, nuts, and seeds. One study found eating just three extra apples or pears a day led to significant weight loss in “overweight” people.
147
(The study just measured short-term weight loss, so don’t take it seriously as a weight loss technique. My point in mentioning it here is that higher fiber eating appears to reduce calorie intake in the short run. This makes sense, given its effect on satiety. And rest assured, increasing fiber is great advice for general health improvement, regardless of its impact on weight.)
Instead of regularly drinking apple juice, perhaps you can occasionally enjoy a juicy apple? Unlike fruit, fruit juice is stripped of the fiber—and is lower in other beneficial nutrients as well.
Choosing Whole Grains
Whole grain products can typically be identified on a food label. Look for the word “whole” in the ingredients list. If you see the word “enriched,” it’s a sure sign it’s not whole grain.
Food companies can sometimes make it difficult to determine which foods are whole grains. Many breads are colored brown and made to look like whole grain, but are not. Also, some food manufacturers make foods with whole-grain ingredients, but, because whole-grain ingredients are not the dominant ingredient, they don’t give you the benefits of a whole-grain product. (Don’t get tricked by small quantities of a whole grain—ingredients are listed in order of weight, so make sure the whole grain appears first.) Another way to identify whole grains is to look in the nutritional facts information and check whether it contains fiber. A significant amount indicates that it most likely contains a good amount of whole grain.
Some grains may not use the word “whole.” Brown rice, for example, is the whole form of white rice, its refined and less nutritious counterpart. “Old-fashioned oats” are the whole form, while “quick” oats are the refined form. Popcorn is another example of a popular whole grain that doesn’t use the word “whole.” Some less common whole grains that may not use the word “whole” include amaranth, buckwheat, millet, quinoa, spelt, sorghum, and triticale.
Bulgur, barley, and couscous are grains that come in both forms, although whether or not they are whole is not always indicated. Pearled barley is refined (not a whole grain).
Another study, this one from Harvard that followed 75,000 women for ten years, found the more fruits and vegetables the women ate, the less likely they were to gain weight over time.
148
And researchers at the National Cancer Institute who followed nearly 80,000 people for ten years found those who ate the most vegetables had the lowest amount of abdominal fat (the type of fat that is more readily implicated in causing harm
149
).
The same thing shows up in research on whole grains: Ten of the eleven studies on this topic reported that the more whole grains an individual consumed, the lower his or her weight.
139
Let me repeat a point made earlier: I am not reporting this research to suggest that a high-fiber diet will result in weight loss—that has not been proven. What I am suggesting is that a high-fiber diet helps you feel satiated on fewer calories. When a food is stripped of fiber, it loses some of its ability to say “enough.” Without this brake in place, you may feel driven to eat more calories than your body needs.
Whole grains haven’t had their bran and germ removed through processing, making them better sources of fiber and other nutrients. Refined grains, on the other hand, such as white rice or white flour, have both the bran and germ removed from the grain. Although vitamins and minerals are added back into refined grains after the milling process, they still don’t have as many nutrients as whole grains do, they don’t provide as much fiber, and they speed through your digestive tract, raising your blood sugar quickly.
Rice, bread, tortillas, cereal, flour, and pasta are all grains or grain products. It’s to your advantage to switch to whole-grain versions, rather than consuming the more accessible refined grains.
Don’t like the taste of whole grains? Future chapters will help you change your tastes. I want you to eat that apple because it’s what you’re craving—not because you think you
should
.
Understanding the different effects refined carbohydrates and whole grains have on your body gives you valuable information to use as you move toward becoming an intuitive eater. Remember that no one food will make or break anything, and the goal is not to deprive yourself of foods you love. If you only like white rice with Chinese meals, enjoy it! Look for other places to include fiber-rich foods. And while it might sound like an oxymoron, the moral is that by
adding
foods to your diet—fruits, vegetables, whole grains, beans, and other fiber-rich foods—you are more likely to keep your weight regulation system functioning at its optimal level.
150
How do you know if you are getting sufficient fiber? There are two easy body clues to be attentive to. The first is having comfortable bowel movements; fiber has the amazing ability to make your stool the right consistency and can help prevent diarrhea as well as constipation. The second clue is having consistent energy and moods throughout the day, as a result of fiber’s role in stabilizing your blood sugar. If you often find yourself on edge and moody, it may just be the result of too little fiber!
High-Fructose Corn Syrup: How Sweet It Isn’t
Now consider the super-sized Cokes that some of us are drinking. Twenty years ago, those Cokes might have been sweetened with a 50-50 mix of sugars made from sugar beets or sugar cane and those made from corn syrup. Today, however, 100 percent of its sweetening comes from high-fructose corn syrup (HFCS). In 1966, we had never heard of the stuff; by 2001, we were annually consuming an average of 62.6 pounds a person.
151
Why? Because it’s plentiful, cheap, and shelf-stable. Not to mention heavily subsidized by the U.S. government and supported by trade restrictions.
High-fructose corn syrup is what helps breads brown and stay soft on the shelf. That’s why you’ll even find it in hot dog buns. It lurks in condiments like ketchup and mayonnaise, in most crackers, even in cough syrup. Since it helps prevent freezer burn, it can be found in most frozen foods—even non-sweet foods like TV dinners. Check your pantry and refrigerator shelves: Chances are HFCS is on the label of every processed food in there, from pasta sauces to bacon, from beer to protein bars and so-called “natural” sodas.
This tremendous jump in high-fructose corn syrup consumption also mirrors the increase in weight, and some scientists put much of the blame for our expanding waistlines on HFCS.
151
That it plays a large role is doubtful, but it does seem likely to be one of the many contributing factors. Three short-term studies found that the more HFCS in the diet, the more people weighed. One possible reason: They didn’t compensate for the extra fructose calories by reducing calories from other sources. Instead, they just kept eating.
152
153
154
Fructose vs. Glucose
How can two sugars act so differently in your body? Though similar, each has a different chemical makeup.
Drink a soda sweetened with glucose—as most are in Europe and other countries—and insulin production increases, allowing the glucose in your blood to be transported into cells and used for energy. The increased insulin production increases production of leptin, which helps regulate appetite and fat storage, and suppresses production of ghrelin, a hormone that increases feelings of hunger. The insulin also travels to receptors on the brain, where it helps regulate appetite and fat storage.
Drink a soda sweetened with fructose—as most are in the United States—and it acts in a totally opposite manner. Because it doesn’t stimulate as much insulin secretion, it doesn’t increase leptin production much. Thus it doesn’t suppress production of ghrelin or activate brain cells to regulate appetite and fat storage.
It seems that while glucose and other sweeteners trigger a “stopeating message,” fructose doesn’t have the same effect on our hunger/satiety signals. So we may add a few hundred fructose calories a day on top of our regular calorie intake without feeling overly full. As you learn to tune into your own signals for hunger and fullness, pay attention to whether this is true for you. Notice if you need more than you would expect when eating large quantities of foods containing HFCS. (This isn’t a foolproof system for knowing what’s going on in your body as the weight regulation mechanisms that HFCS bypasses also play a role in long-term weight regulation, not just meal-to-meal satiety.)
Researchers are not unified in implicating high-fructose corn syrup, noting that old-fashioned sugar is already half fructose, and even high-fructose corn syrup is generally no more than 55 percent fructose. The issue may be related to quantity. Today, about one-sixth of all our calories and 13 percent of all carbohydrates come from HFCS.
155
Wondering how plentiful high-fructose corn syrup is in your diet? Just check the ingredients list on food labels: It should be clearly specified.
Fat = Fat?
Another nutrient that affects your weight regulation system is fat. Fat consumption has clearly increased over the years: Americans ate an average of 523 more calories in 2003 than in 1970.
157
158
Interestingly, while the
percentage
of fat in our diet has dropped (given our overall increase in calories)
159
much of the fat we’re eating today is
added
fat, as opposed to naturally occurring fat in foods. Average consumption of added fat jumped from 53 pounds per person in the 1970s to over 74 pounds in the year 2000, a 40 percent surge.
157
Why does this matter? Well, consider that most dietary fat—especially the stuff that gets added—has even less of an impact on leptin secretion than fructose. Ergo, it doesn’t trigger those sensors that tell us it’s time to stop eating, so it may contribute to that higher setpoint.
Need proof? Consider a study from my colleagues at the University of California, Davis. They found that women consuming a high-carbohydrate, low-fat diet released 40 percent more leptin than those consuming a high-fat, low-carbohydrate diet.
160
Other research finds that, ironically, consuming a high-fat diet can increase your desire for more food!
161
Why? Well, if high-fat diets don’t stimulate leptin release, you’re not getting the appetite-suppressing effects of leptin. Fat is also less effective than protein or carbohydrates at suppressing ghrelin’s hunger call.
162
So it may take more fat calories to satisfy you. Numerous other studies suggest this decreased leptin production from high-fat diets leads to increased eating and weight gain.
163
164
165
166
167