Thrive: The Vegan Nutrition Guide to Optimal Performance in Sports and Life

problems are caused by stress. Obesity, fatigue, mental fog, sleep disturbances, digestive problems, prematurely wrinkled skin, depression … the list goes on. If stress, and therefore cortisol, remains elevated, several problems arise to hamper our body’s smooth functioning. One is that the body shifts fuel sources. Instead of burning fat as fuel, a stressed person’s system will burn carbohydrate in the form of sugar, and the body begins to store the body fat instead of using it for energy. Stress-free people are fat-burning machines. Stressed people, on the other hand, burn and in turn crave carbohydrates. And cravings themselves are a form of psychological stress, as I discuss later in this chapter.
     
    Stressed people do not burn body fat as fuel as efficiently as do those who are not stressed.
     
     
    Stress can also cause hormonal imbalance. When cortisol levels change rapidly, the hormone’s symbiotic relationship with other hormones is altered. Hormone imbalance may, for instance, affect electrolyte function, reducing the body’s ability to stay adequately hydrated. This results in muscle cramping in the short term and, if neglected, wrinkled and less elastic skin. When the body has difficulty maintaining optimal fluid levels, the delivery of nutrients to its cells is compromised. This leads to a host of problems—basic malnutrition being the most obvious. Even if the diet is ideal, the nutrients are of little use if they don’t get distributed. Hormone imbalance can also cause slowed mental ability and impair the delivery of messages from the brain to other parts of the body, slowing movement.
     
    Another health concern that regularly crops up as stress mounts is the inability to sleep soundly. We have all likely had difficulty falling asleep after a traumatic event, or perhaps even after taking on a new, uncertain project at work. As you probably suspected, high cortisol levels are again to blame. And lack of sleep further raises cortisol levels. It’s a vicious circle: The body has an increased need for sleep at heightened times of stress yet is unable to get it.
     

my introduction to stress
     
    I learned a lesson the first year I decided to compete in longer races. It was the spring of 1997. I gradually, but significantly, increased my training mileage, by about 10 percent per week. The first few weeks I didn’t experience any problems; everything felt good. But as the months wore on and spring became summer, I found that as my rate of exercise increased, my quality of sleep decreased. This was strange. I had assumed that the more exercise I did, the more tired I would be and the better I would sleep. I continued training as usual. As the weeks passed, the quality of my training declined and I developed a greater appetite.
     
    I was putting my body under a great deal of physical stress. As a result, my cortisol rose to a level that adversely affected my sleep quality. Cortisol levels, if elevated high enough, inhibit the body’s ability to slip into the deep sleep state known as delta. It’s in the delta phase that the body is best able to restore and regenerate itself. Taking longer to reach delta shortens the time spent in this phase if the total sleep time remains the same. Therefore, to achieve the same restored effect, the body needs to sleep longer.
     
    To maintain the quality of my training sessions, I had to sleep almost an extra hour each night. By doing so, I got my season back on track and was able to retain my desired level of training. At the time, I didn’t realize the cause and so treated the symptom, allowing myself to sleep longer. This method worked but, as I understood later, was far from optimal. Reducing the amount of training would also have treated the symptom, but that too was a far from optimal solution. At the time, my nutrition program was adequate but certainly not great. Some of the stress I was experiencing was certainly nutritionally based. Had I nourished my overworked adrenal glands with high-quality whole foods, my sleep quality would have improved enough to get me back on track.
     
    An even more mysterious situation occurred the following year, my second of full-time Ironman training. I was putting in 8- to 10-hour training days, but despite performing 40 hours of exercise per week, I began to slowly accumulate body fat. Not much, about a pound per week, but it was noticeable, and the extra weight was decreasing my strength-to-weight ratio. How