How would you describe your metabolism? Do you feel like you can eat whatever you want and easily burn the calories off? Or do you feel like everything you even think about eating turns to fat?
What if you could speed up your metabolism so that more of what you eat turns to energy, rather than being stored as fat? That would be handy, wouldn’t it?
Some people seem to think that you have to exercise to speed up your metabolism. But in our research, we have found that you can do just that simply with food. By choosing the right foods, you can reprogram your cells to speed up their metabolism after every single meal. In this chapter, I’ll show you how we proved this and how you can easily do the same thing.
Picture a wood-burning stove. If you throw in a few twigs, you’ll get a small flame. Throw in some hefty logs, and you’ll get a sustained burn.
Or picture a car. If you squirt in a little gas, you can rev up the engine for a mile or two. But fill the tank with the right fuel, and off you’ll go.
Your body needs fuel, too. Not logs or gasoline, of course. The main fuel your body uses is glucose. It powers your movements, maintains your body temperature, and keeps your organs functioning.
Glucose is actually a natural sugar, and it comes from foods. You’ll find it in starchy foods, like bread, rice, beans, potatoes, and pasta, and also in fruits, such as apples, bananas, peaches, pears, and others. During digestion, glucose passes from the foods you eat, into your bloodstream, and then into your body tissues.
Metabolism is the process of turning fuel into energy. If you have a “fast metabolism,” you have what is essentially a little inferno inside each cell. You’re burning lots of calories minute by minute. The faster your metabolism, the faster you’re burning up calories, and the less fat you’re storing.
Just looking at people, you can’t tell how fast their metabolism is. But if you were a volunteer in one of our weight loss studies, we could measure your metabolism. We would ask you to lie down on a typical examination table and breathe normally. Over your head and shoulders, we would place a special see-through canopy that allows us to track how much oxygen you’re taking in and how much carbon dioxide you’re breathing out. With a few simple calculations, we can tell precisely how fast you are burning calories. We can also track how this changes over time.
“But what difference does it make?” you might ask. “Isn’t it all genetic? I can’t change it.”
Well, not so fast. Hold that thought for a moment.
Every time you have something to eat, almost instantly, nutrients pass into your bloodstream and then into the cells of your body, where they are converted to energy. Like throwing more fuel on a fire or pressing the gas pedal in your car, your metabolism quickens. And it stays slightly higher than normal for three hours or more, thanks to the food you’ve eaten. This happens more or less anytime you eat.
But is that extra burn just a little after-meal flicker, or is it a major flare? Is there a way to turn that flame higher?
In one of our studies, we measured metabolism in a group of older people with chronic weight problems. We then asked them to eat differently for the next several weeks. Specifically, we asked them to stick to entirely plant-based meals and to keep oils to a minimum—the kind of diet described in the preceding chapter. We gave everyone recipes like those in this book.
Later on, we invited everyone to come back to the laboratory, and we tested their metabolic rates again. They lay on the table and breathed into the canopy. We found that not only did their calorie-burning speed jump up after a meal—but that extra burn was significantly higher than it had been when the study started.
In other words, even though everyone gets a little calorie burn after eating, something about their special dietary plan ramped up their responsiveness, so their bodies burned calories even faster. These were the same people, in the same room, lying on the same table. We gave them exactly the same test meal. But their after-meal calorie burn was bigger. It was like turning a burner on your stove from medium to high. They were converting more food into energy, instead of storing it as fat.
On average, they were burning calories about 16 percent faster for about three hours after the meal. Now, for any given meal, that’s a modest change. But if you can burn calories faster for three hours after breakfast, three more hours after lunch, and again after dinner, you’re getting a bigger burn. Imagine if you were to set your car’s engine to rev higher for a few hours at a time, several times a day, day after day. Over time, you would burn up quite a lot more gas. If the cells in your body rev up as well, you’ll have an extra edge that helps you trim away extra weight.
How does this happen? How can foods boost your metabolism?
It turned out that the diet adjustment our research participants had made caused a fundamental change in their bodies. It reprogrammed their cells to pull sugar out of the blood more quickly, so it could be burned.
Here are the details: Normally, the hormone insulin escorts sugar and protein from your bloodstream into your cells. If insulin shoots the nutrients from foods into your cells rapidly, they can be quickly converted to energy. But insulin’s ability to shoot those nutrients into the cell depends on how much fat has built up inside the cell.
If you had a very powerful microscope that could look inside your muscle cells, you would see something that might alarm you. Fat from the foods you eat forms tiny droplets that seem to float inside each cell.
Now, a small collection of fat droplets in each cell is perfectly normal; everyone has some of them. But if you’ve accumulated quite a number of fat droplets, they interfere with insulin’s efforts to move glucose into the cells.
Let me be clear. These are fat droplets inside your muscle cells. This is not a fat layer padding your waistline or rounding your hips. These microscopic bits of fat are lurking deep within the individual cells of your body. Scientists call them intramyocellular lipid, which is simply another way of saying fat inside your muscle cells.
I liken this situation to chewing gum in a lock. If some troublemaker put chewing gum into your front-door lock, your key would not work very well. Insulin is like a key. If you have a great many fat droplets packed into your muscle cells, the insulin “key” has trouble opening the cell membrane to allow glucose inside. If glucose can’t get in, it can’t be converted to energy. For some people, things get even worse: The buildup of fat inside cells leads to serious insulin resistance and eventually to type 2 diabetes.
Those mischievous fat particles come from the foods you eat. Let’s look at a high-fat meal. It might start off with a salad drenched in an oily dressing, followed by spaghetti with meat sauce topped with cheese, and fried onion rings. All these foods contribute a load of fat. And into your cells it goes, interfering with your after-meal calorie burn.
We would have done better to top our salad with a nonfat dressing or a delicious plum vinegar and to add a chunky tomato-and-mushroom sauce to our spaghetti. Instead of onion rings, we might have had steamed asparagus. We’d have cut our fat intake dramatically.
Normally, your cells can burn up some of the fat you are consuming. Each cell has tiny particles, called mitochondria, which are like little burners, and they do their best to metabolize fat. But when you eat too much fat, these burners no longer work very well.
Scientists in Baton Rouge, Louisiana, asked ten healthy men to eat more fat than they normally would—about half their calories came from fat, compared with the more usual fat intake, which is about one-third of calories. After three days of fatty foods, the researchers removed tiny samples of each man’s muscle cells in order to examine them carefully. It turned out that the cells no longer functioned normally. The fatty foods had partially turned off the genes that produce mitochondria. In other words, fatty meals didn’t just put more fat into the cells; they also reduced the number of mitochondria “burners” in their cells. And that makes it harder to burn away fat.1
What all this means is this: You want nice, clean cells, without a lot of fat inside, because a clean cell can pull in glucose and convert much of it to energy. But fatty foods can pack fat into your cells, like chewing gum in a lock. And when that happens, glucose has trouble getting inside, and your metabolism gets no boost. And it is as if your body is greedily storing fat. With fewer mitochondria to burn it up, fat continues to build up in the cell. And you’re not getting the after-meal burn that you should have.
So how can we remove the fat from our cells and get our metabolism back? Well, one way is rather drastic surgery, not that I recommend it. Researchers at Catholic University in Rome, Italy, performed a procedure called a biliopancreatic diversion on eight severely overweight adults. The procedure, which is more involved than stomach stapling, cuts the stomach down to a very small size and completely disconnects the part of the intestine that absorbs fat from foods. After the procedure, you cannot eat very much of anything, and virtually all the fat you eat just passes through you and into the toilet.
The result was dramatic. Not only did the participants lose weight, but the amount of fat in their cells—the intramyocellular lipid that was interfering with their metabolism—dropped by 87 percent! Needless to say, there are plenty of disadvantages to a surgical approach, and, again, I am certainly not recommending it. But this experiment proves that, if fat can no longer get into your body, it starts to leave the cells.
Happily, there is a much easier way to evict this undesirable fat from your cells. And that is to leave fat out of the foods you eat. At Imperial College School of Medicine in London, researchers looked to see whether people who avoid meat and other animal products might have less fat in their cells.2 After all, they are avoiding all the fat in beef, pork, cheese, and other animal products.
The researchers recruited a group of people who followed an entirely plant-based diet, and measured the fat in their cells. As you might have guessed, they had about 30 percent less fat in their cells, compared with meat eaters. In other words, by skipping many common fatty foods, they had less fat in their cells.
Well, what if you went a step further? What if you not only avoided animal fats, but you also steered clear of most vegetable oils? You could choose nonfat dressings, throw out the greasy fries, and steam, broil, or bake your foods, instead of frying. That would cut even more fat from your diet. And it would probably reduce fat in your cells even more, right? Well, that is exactly what we were doing in our research study. The participants ate no animal products and kept vegetable oils to a minimum. And their after-meal calorie burn got a boost very quickly.
So the secret is this: If you take most of the fat out of your diet, each lean little cell responds to insulin much more quickly. It pulls sugar out of the blood, and converts more of it to energy. Your cells become supercharged, ready to burn off calories faster.
“Wait a minute!” I hear you say. If this diet change makes insulin work better and pulls sugar out of the blood, it sounds like a good treatment for diabetes! As a matter of fact, that’s what we thought, too. In 2003, the National Institutes of Health awarded our research team a grant to see just how good a diabetes treatment it is. And the results of our study changed the Clinical Practice Recommendations of the American Diabetes Association. We’ll look at the details in the next chapter. In the meantime, let me share with you an experience that occurred many thousands of miles from our research center.
The Marshall Islands are a group of twelve hundred atolls and islands—many of them very tiny, but all very beautiful—in the Pacific Ocean, northeast of Australia. Between 1946 and 1958, the US government conducted extensive atomic weapons tests in the islands, with a great many effects, all of them negative. Apart from the obvious problem of widespread radiation exposure, some residents were displaced from one island to another so the testing could go forward. And American food products became big sellers, particularly Spam. This nondescript meaty loaf in a can filled the shelves in grocery shops, along with sugary drinks and snack foods. And before you could say “intramyocellular lipid,” diabetes became rampant.
In many other parts of the world, a similar scenario is playing out, except that instead of Spam, the Western import is hamburgers, chicken nuggets, cheese pizza, or fried chicken. The fatty food tsunami carries diabetes along with it.
However, there has been a bright spot between the clouds in the Marshall Islands. A medical group called Canvasback Missions gathered together diabetes experts, including John Kelly, MD, and registered dietitian Brenda Davis, to set up the Diabetes Wellness Project with funding from the US Department of Defense. And to its lasting credit, the project de-Spammed the diets of people with diabetes who visited them. The team used a plant-based diet that happened to be much more in sync with the traditional Marshallese diet—the kinds of foods consumed before the arrival of Americans, atomic weapons, and Spam.
The program made an enormous difference. People with diabetes found themselves losing weight and reducing or eliminating medications; in some cases, their diabetes was no longer detectable.
One participant was a thirty-eight-year-old pilot. Or ex-pilot, I should say. When a routine employment physical showed diabetes, it ended his career, right then and there. He was married, with two children. His work supported his family, and he loved it. But diabetes meant he was no longer allowed to pilot an airplane. Period.
Then he happened to discover the Diabetes Wellness Project, which taught him how to prepare healthy plant-based foods. And bit by bit, he started to get better. He added exercise to his regimen, and not long after joining the program, he had this to say:
I completely changed my diet and began a daily exercise program. Upon my last physical checkup, I was told that I am fully recovered and my pilot’s medical certificate was approved. My fasting sugar is below 90 mg/dL with no medications. I no longer have diabetes. I have my career and my life back.
So now you have two powerful paths toward permanent weight control—an ability to rein in your appetite and to also boost your calorie burn. One deals with “calories in,” and the other with “calories out,” and they are fundamental to the success of the Kickstart. Best of all, the same foods that bring these benefits help you stay young and healthy. Let’s turn to cardioprotection, the third of the Kickstart ABCs.