The Mile-High Metabolism
CHAPTER 2
The word metabolism gets tossed around a lot, but most people aren’t sure what it means. Put simply, metabolism is the process by which the body converts food to energy it can use. It’s the sum of all the chemical reactions and physical processes that occur in our bodies—from hormone production, to digestion, to pumping blood, to breathing, to walking, and more. Even when you’re asleep or sitting completely still, your body needs energy to keep it going, so your metabolism is active around the clock.
In an ideal world, your metabolism adapts to your diet. You burn all the calories you consume, regardless of whether they come from protein, carbohydrate, or fat, and if you eat a little more or less on any given day, your metabolism compensates by speeding up or slowing down. That’s what we call a Mile-High Metabolism—one that quickly adjusts to your calorie intake and activity level. The human body is built to move, and it needs high-octane fuel to function at its best. When your body stops moving as it was intended to or if you supply it with inferior fuel, your metabolism begins to deteriorate. You become more efficient at storing calories, in the form of body fat, than burning them.
The Colorado Diet repairs your metabolism so that you can stop stockpiling fat and prevent those unwanted pounds from creeping up on you.
YOUR BODY, THE BATHTUB
Most diet plans focus on reducing the amount of water that flows into the tub by slowing the faucet to a trickle (restricting food intake). That works for a while. Eventually, though, the water level begins to creep up again—slowly if you keep the faucet on low, but very quickly if you happen to turn the knob higher. Why? Because the drain is clogged. However, if you fix the drain while the faucet is on low, you can reduce the tub’s water level and later turn the faucet back up and still keep the water level low.
To get to a healthy weight and stay there, you have to completely revamp your tub. That requires three things:
1. Turning the faucet down temporarily so the water level is lowered
2. Unclogging your drain and increasing its diameter so water flows more freely—even when the tap is on full blast
3. Adjusting your faucet to match your drain’s capacity and keep it clear
Using this bathtub analogy, having a Mile-High Metabolism means your drain (metabolism) automatically responds to the amount of water (food) coming in so the water level in your tub (your weight) stays steady.
The ability to adjust to your changing food intake and switch between carbohydrates and fat for energy is known in scientific circles as “metabolic flexibility.” Genetics plays a role in metabolic flexibility, just as it does in height and eye color. Some people, such as the “easy gainers” we describe in “What’s Your Metabolism Personality?” (this page), are naturally more likely to drift into fat-storage mode than others, while those skinny kids who can’t for the life of them gain weight are genetically programmed to maintain a high level of metabolic flexibility. But the good news is that unlike height and eye color, metabolic flexibility is a trait that you can influence with your behavior. Everyone has the capacity to develop a Mile-High Metabolism.
GETTING OUT OF FAT-STORING MODE
You often hear that extra protein and carbohydrate calories are converted to fat. Except under extremely rare circumstances, this isn’t true. So what happens to the carbohydrate and protein you eat? No matter how much of these two nutrients you consume, you can only store a tiny amount of each. All of the rest is burned. That does not mean that you can eat as much of them as you want, though. If you have a surplus of carbohydrate and protein, your body will use them at the expense of fat. They may not turn into fat, but they shut off fat-burning.
To understand how, you need to know how the body uses two hormones, insulin and leptin. Carbohydrate, and to a lesser extent protein, stimulates the pancreas to produce insulin. Insulin’s job is to shuttle glucose (the end product of carbohydrate digestion) from the bloodstream into cells where it can be used for energy or stored as muscle glycogen (the liver can also store some glycogen). It also promotes uptake of amino acids from protein digestion into muscle cells to support normal muscle repair. (Any excess amino acids are burned for fuel.) Your body will not burn fat while your insulin level is high. It’s focused on using glucose. But once all of the glucose and glycogen is used, the insulin level falls and fat is readily released from your fat cells to keep your body going until your next infusion of glucose.
When you overconsume protein and carbohydrate, though, your insulin level never gets low enough and your body doesn’t get a chance to tap into its fat stores. What’s more, any fat you do eat is shuttled directly into your fat cells for storage, adding to the fat that’s already there—and you gain weight.
(You can’t get around this by cutting all fat out of your diet. First, for practical purposes it’s impossible. The vast majority of foods are some combination of protein, carbohydrate, and fat. For instance, while beef is mostly protein, even lean cuts have some fat. Avocados and nuts are mostly fat, but they also contain protein and carbohydrate. But even if you were able to reduce your fat intake to zero, your body would convert excess carbs to fat, that being one of the extremely rare circumstances we mentioned above.)
If you have a Mile-High Metabolism, you never get to this point, thanks to the action of leptin. Fat cells produce this hormone when fat storage is adequate to signal the brain to reduce appetite. You feel full, you stop eating, your insulin levels drop, and your body burns some of its stored fat. Fat cells then need to be replenished, so they stop making leptin and that stimulates appetite.
If you override leptin’s signal and keep eating, your fat cells get larger and produce even more leptin in an effort to get your brain to stop you. Keep ignoring leptin’s call, though, and the communication loop breaks down. Your brain becomes resistant to leptin—the signal to reduce food intake is there but the brain doesn’t recognize it—and appetite increases. Your body is no longer in harmony, and your metabolism has become inflexible.
EXERCISE IS YOUR DRANO
The kind of food restriction required to maintain a lower body weight is unsustainable—and you can’t keep turning down the spigot forever. Your body is programmed to operate with an open spigot. Humans have a strong biological instinct to eat a lot of food because a few thousand years ago, food was more scarce and our ancestors had to work hard to obtain it. As a result, we developed a tendency to eat our fill when food is available and to store extra energy by building up our fat reserves so we’d have resources when there wasn’t much around to consume. Our lifestyles and eating habits have changed enormously since then, but the human body has not. Restricting food, especially when there’s plenty of it available, is something that we simply aren’t programmed to do.
When you stop moving, buildup begins in your drain: Metabolic harmony is gradually disrupted, and your metabolism becomes less and less flexible. Eventually, your drain clogs. Muscles become resistant to insulin, so their ability to switch from carbohydrate to fat as a fuel source slows. The number of mitochondria—the power centers of cells that convert carbohydrate and fat to energy—in muscle tissue declines. There is also a reduction in those muscle fibers that burn fat best. The body tries to compensate for muscle insulin resistance by pumping out more insulin. This inhibits fat release and triggers fat storage. The result is larger fat cells.
In our weight loss clinic, we tell people that if they aren’t prepared to increase their movement substantially, their chances of being successful over the long term are low. Losing weight without increasing physical activity makes it practically impossible to relax your diet vigilance even a little. When you are physically active, you burn the fuel you take in. The spigot is wide open, but so is your drain, so very little water builds up in the tub. And that’s how people pretty much lived until the mid-20th century, when our drains started to get “clogged” as we slowed our physical activity.
Even the decline in activity levels over just a few generations has made a difference in our metabolisms. A study led by Dr. Tim Church at the Pennington Biomedical Research Center looked at changes in physical activity in the workplace from the 1960s to the present. He calculated that today’s sedentary workers expend 140 to 160 fewer calories per day in physical activity than office workers of the past. Overall, the amount of physical activity required for the routine tasks of daily living (such as washing dishes and clothes, preparing meals, mowing the grass, and getting from point A to point B) is less than it used to be, in great part due to technology. But there’s one group of Americans who still live the way we did at the start of the 20th century: the Amish.
People in Amish communities lead lifestyles that resemble a typical American’s lifestyle in the late 19th and early 20th centuries. They walk most places or drive horse and buggies and farm in a way that relies on human power. The Amish eat a diet very much like the one most people ate 100 years ago—meat, potatoes, homegrown vegetables, and homemade pies and other baked goods. It’s obviously not a low-calorie diet, yet obesity rates in these communities are extraordinarily low: zero for men and just 4 percent for women.
What’s the Amish secret? It’s their active lifestyles. Dr. David Basset Jr. at the University of Tennessee found that in a typical day, the Amish men walk an average of 18,000 steps (about 8 miles), while Amish women get 14,000 steps (more than 6 miles). All that activity gives them the metabolic flexibility to burn what they eat and helps regulate appetite so their bodies tell them when to stop eating naturally. This is the way everyone’s body was intended to work, but most people don’t move enough to keep their metabolism running properly.
It doesn’t take very long for a lack of movement to begin to clog your drain. Dr. Audrey Bergouignan, our colleague at the University of Colorado, showed just how quickly it happens. She reviewed 60 years of research on bed rest—and that’s about as sedentary as you can get! In these studies, active people volunteered to undergo complete bed rest for periods that ranged from a few days to several months. What Dr. Bergouignan learned was amazing. People’s metabolisms began losing flexibility after just a single day. Now imagine what 10 years of inactivity can do to your metabolism.
GET YOUR APPETITE IN THE REGULATED ZONE
Studies in the 1950s by Tufts University scientist Jean Mayer were the first to reveal this paradox. Dr. Mayer examined food intake and body weight across a range of occupations, in hundreds of people from sedentary office workers to farmers and laborers. Without any deliberate calorie counting, workers in jobs that required some physical activity matched their food intake to their energy demands, so their weight stayed healthy and stable.
But here’s where it gets interesting. Mayer found that people in the most sedentary occupations ate far more calories than they needed to meet the energy demands of their jobs, and these workers were much more likely to be overweight and obese. The message was clear. People whose daily lives required physical activity maintained precise appetite control and food intakes, while those living a sedentary lifestyle did not adjust their food intake downward to match their tiny energy expenditures—and they gained weight.
SURPRISE: YOU DO NOT NEED TO EXERCISE TO LOSE WEIGHT
However, you must exercise to keep the weight off. Lasting weight loss is really a two-part process. Step one is to temporarily turn down your spigot (eating less) to bring the water level (your body weight) down. But if the drain is still clogged, the water level will inevitably rise again.
Step 2 is to clear your drain—boost physical activity—so it can handle a stronger flow of water. According to our research and our analysis of data in the National Weight Control Registry, physical activity level is the best predictor of who will be successful in keeping weight off. Movement will fix your metabolism. This doesn’t happen with just a few exercises sessions—typically it takes about 16 weeks—but the more active you are, the better your metabolism will function.
By developing a Mile-High Metabolism, you avoid having to restrict your food intake permanently. Once your drain is open, you can turn up the spigot. You can maintain your weight loss with a diet that is reasonable and filling. Yes, you have to learn to eat smarter, but you don’t have to spend all day being hungry and counting calories.
A PARADOX
Modern life is notoriously sedentary, so you’d expect that desk jockeys would have much lower daily energy (calorie) expenditures than our nomadic ancestors or populations who still require lots of exercise for daily living. But it turns out that this isn’t the case. Recent research shows that the number of calories that today’s hunter-gatherer people burn each day is about equal to the calories sedentary office workers burn. Yet those populations are lean and fit and our contemporary American population is fat and unhealthy.
How can this be? It turns out that active and sedentary people reach a similar level of energy expenditure by two very different paths—being physically active or by gaining weight. Here’s how it works: We previously explained that if you gain weight, you require more calories just to keep your now bigger body alive. Your body wants to consume a lot of food, and there are really only two things it can do with these calories—burn them or store them. If you move more, you burn more; if you’re sedentary, the extra calories result in weight and fat gain. As your weight increases, you burn more calories. This is because it takes more energy to maintain and move a bigger body than a smaller one. This is the way our modern bodies have developed to burn the calories we are eating without doing more exercise. Modern hunter-gatherers move more and store less, and consequently, they’re lean, smaller people. Typical sedentary Americans, on the other hand, store more calories and gain weight to get to the same level of total energy expenditure as our active hunter-gatherer ancestors without doing all the movement.
A TALE OF TWO DIETERS
Jessica’s Path
Around this time, though, her weight loss slows. She discovers that she has to eat even fewer calories than she currently eats to lose any additional weight, and it’s not easy. She spends a lot of time every day thinking and worrying about what she eats.
The next 5 pounds take several weeks to come off, and the next 2 pounds take even longer. After about 4 months, her weight is officially “stuck” at 202 pounds. She’s hungry all the time. Her willpower fades, and she starts to eat “off” her diet plan—just a few bites here and there.
Over the next 6 months, Jessica tries to eat well, but slowly she regains some of the weight she lost. That frustrates her because she really doesn’t believe she is eating very much. She thinks she should be able to eat a slice of pizza every now and then, but it seems as though anything she puts in her mouth that is not “perfect” causes her to gain weight. Sometimes, she throws in the towel and eats whatever she wants. She begins to think she was just not meant to be lean.
Rebecca’s Path
On phase 3, her food choices become more varied again, and she gets to have some treats. This keeps her confidence and her determination high. She loses another 15 pounds in the next 8 weeks. After about 4 months, she weighs 185 pounds. She is surprised to see that she is eating about the same number of calories as she was eating before her weight loss, but now she is eating much better food. She now also gets about 70 minutes of activity a day, and she’s burning a significant number of calories.
Rebecca continues to eat smarter and exercise over the next 6 months. She is energized and has created a new life for herself. She joined a gym and really likes the Zumba classes. She starts a walking group with three other women in her neighborhood. She begins each day by thinking about how she will meet her exercise goal that day. She feels satisfied because she can eat a lot of good food and can have an occasional treat. When she notices her weight creeping back, she returns to phase 1 for a few days. She finally feels that she has the right tools to manage her weight forever.
Rebecca, on the other hand, feels satisfied because she can eat a lot of good food and can have an occasional treat. Not only did she lose weight, she changed her lifestyle so the weight stays off. She has achieved a Mile-High Metabolism, which means she has metabolic flexibility and enhanced capacity to burn rather than store fat. As long as she eats smart and continues to meet her activity goal of 70 minutes of activity per day, 6 days a week, she will not regain her lost weight.
The Colorado Diet allows you to lose weight and end up with a Mile-High Metabolism and a lifestyle you can sustain forever. Now it’s your choice: Do you want to be a Jessica or a Rebecca?
WHAT’S YOUR METABOLISM PERSONALITY?
Hundreds of patients have come through our weight-loss clinic, and we’ve noticed that their weight troubles almost always trace back to the fact that their diets and their metabolism are not in sync. Here are three types of people we see frequently. Chances are, you’ll see yourself in one of these real-life stories of “broken metabolism.”
The Easy Gainer:
I have to eat perfectly to lose weight and keep it off
Joanne walked into our office carrying months of meticulous food diaries logging every bite she’d ever put in her mouth. Over the previous 3 months, she’d lost 30 pounds, but instead of feeling ecstatic, she was worried. She’d been here before. She would religiously follow a diet and the pounds would peel off, but the moment she allowed herself even a small indulgence—the second she so much as set eyes on a cookie—she’d gain it right back. She’d returned from a recent vacation 10 pounds heavier than when she’d left. She wanted to slim down, but she was tired of having to track every morsel. It seemed that she never had time to think about anything but food.
We call dieters like Joanne the “easy gainers.” Their metabolism lacks any flexibility at all, so their bodies pack every single extra calorie onto their hips (or butts or bellies). For them, losing weight requires extra effort—more so than some of their peers. (It’s unfair, we know.) Easy gainers have super-inflexible metabolisms. It’s much harder for their bodies to turn on fat-burning simply by cutting back on what they eat. Joanne’s 10-pound weight gain over a 2-week vacation is typical for people like her, most of whom have struggled with weight problems since childhood.
Joanne was on the verge of giving up when she came to us. She was tired of being hypervigilant about the food she ate and knew that something was wrong with her metabolism—and she was right! But her situation was far from hopeless. What she needed was a metabolism transformation. By moving her body and by learning to eat smarter, she was able to maintain her weight loss without having to spend every waking hour thinking about food.
The Healthy Over-Fueler:
I eat so healthy but never lose weight
Paula is a high school teacher, happily married with two young, active children. Her husband and kids are slim and healthy, but Paula struggled to lose the 20 pounds she’d gained with the birth of her last child. It wasn’t for lack of trying. Making healthy meals for her family was a top priority, and Paula is well versed in nutrition. When we asked her to recall the foods she’d prepared over the previous weeks, she recited a long list of healthy items—whole grain breads, brown rice, fish, grilled chicken, almonds, natural peanut butter, berries, hummus, olive oil, walnuts, and lots of vegetables. She banned sugary soft drinks and favored whole foods over processed ones. Her occasional treats consisted of low-fat frozen yogurt or pudding. Paula wasn’t supersizing her portions, and her family limited meals out to once per week. The whole family enjoyed physical activity together on the weekends, and Paula walked several times a week with some ladies in her neighborhood. She felt her lifestyle was pretty good, but her weight would not budge.
We see lots of people like Paula—we call them the “healthy over-fuelers.” They’re frustrated, and rightfully so. They’re doing almost everything right—they’re eating the right kinds of foods and engaging in some exercise. The level of water in their tubs is not going up, but it’s not going down either. Their weight is stable but higher than they like.
Paula’s problem was that she had mastered the art of weight maintenance, but she’d skipped the weight-loss step. Her moderate level of physical activity kept her metabolism from being too inflexible. But she was stuck, and to get unstuck we recommended phases 1 and 2 of the Colorado Diet. Paula needed to limit the amount of water flowing into her tub and to open the drain a little more by increasing her physical activity. She lost weight on the Colorado Diet, and then she went back to her healthy eating (which she had already turned into a habit). Increasing her physical activity to 70 minutes a day made it possible for her to maintain the lower body weight she achieved.
The Aging Gainer:
I can no longer eat whatever I want and stay lean
Tom walked into our office a few days after his 50th birthday. With an exasperated look on his face, he lifted his shirt and pinched a layer of fat on his belly. Up until a few years ago, he said, there was a six-pack where that roll of fat now hung over his waistband. In his twenties and thirties, Tom could eat whatever he wanted and never worry about his weight. He was moderately physically active but never felt that he had to go out of his way to make sure he hit the gym every day. Tom had never thought much about his lifestyle. Maintaining a healthy weight was something that happened without much effort. Then he turned 45, and it was like a switch flipped. Suddenly, his body stockpiled every extra calorie and stuffed it into the bulges of fat that kept covering up muscles that used to be visible.
Tom represents what we call the “aging gainers.” It’s an unfortunate fact of life that as you get older, your muscle mass naturally begins to decrease—by 5 to 10 percent per decade after about age 40. Consequently, the number of calories you burn decreases, and many people tend to put on some fat. While exercise can help reduce loss of muscle with aging, exercise can’t prevent it totally. It’s a process that happens so gradually that you may not notice it until one day, like Tom, you wake up with a pot belly.
A sluggish metabolism may feel like an added insult to an aging body, but unlike thinning hair, it’s a problem you can do something about. The solution involves changes to both physical activity and diet. Even though Tom considered himself active, he had to ramp it up a little more. His natural Mile-High Metabolism was naturally slowing down. Adding more exercise helped limit the decline, but now he had to pay attention to his diet. His aging metabolism no longer allowed him to eat anything he wanted. He had to learn to eat smarter to match his diet to his changing metabolism. With this strategy, Tom lost 15 pounds, shed his spare tire, and regained his flat belly. He had to pay more attention to his lifestyle than before, but it was worth it.