The connection between nutrition and stamina is straightforward: food is fuel. along with oxygen it is our primary source of energy. just as we will become fatigued and perform at a lower level when deprived of enough oxygen our energy will drop off when given inadequate nourishment. that is why in this chapter we are going to focus on how the choices we make regarding what we eat and drink can either support—or undermine—our objectives in key areas of stamina: keeping our energy level high without drop-offs strengthening our immune system and increasing longevity maximizing the fitness gains from our workouts helping our bodies recover from stress and experience deep sleep providing good nutritional options while traveling in the previous chapters on fitness we explained that you need to transition slowly from your current level of activity to the eventual workout plan you aspire to.
Doing so takes into account your current habits and how slowly the body adapts to change. nutritional habits tend to be even 137 more ingrained reinforced by family traditions culture advertising—even our taste buds. so when it comes to improving your nutrition we recommend gradual change and stress improvement not perfection. to that end we will guide to you transition to different patterns gradually. nutritional overview fortunately these days it is easier than ever to make healthy food choices. public concerns consumer demands and in some cases regulatory changes are pushing food manufacturers restaurants and even the media to focus on a better for you approach. of course easier doesnt mean easy. that is why our goal in this chapter is to offer you key concepts to serve as a guide to your day-to-day decision-making process where food is concerned and to provide you with many simple convenient choices that can help you move in the direction of high-stamina eating. we divide these concepts into three categories: nutrient-rich foods glycemic index nutritional alerts nutrient-rich foods to look and feel our best and to be able to perform effectively we need an array of vital nutrients. besides the right amounts of carbohydrates proteins and fats we need minimum quantities of minerals vitamins and micronutrients antioxidants and phytonutrients the challenge is to ingest these nutrients at the right times and in many cases in the right combinations and absent excess and unnecessary calories. the place to start is with nutrient-rich foods.
What does that mean when a food yields a rich supply of essential nutrients without excess calories scientists refer to it as nutrient dense. george mateljan in his book 138 nutrition the worlds healthiest foods george mateljan foundation 2007 has compiled a list of the top 100 foods that meet this criterion which he calls nutrient rich. not only do they provide maximal nutritional value per calorie they are all whole foods that contain combinations of vitamins minerals fiber and micronutrients which enable full absorption by our bodies. whole foods are important because research indicates that many nutrients are lost in processing or in overcooking and so we also lose the essential nutritional combination that nature has provided. science is still in the early stages of figuring out the role of various nutrients in ensuring our health and vitality. this is understandable given that food scientists estimate there are more than 40 000 phytonutrients micronutrients found in plants in our food. heres just a small sampling of recent discoveries in this field of study: a team of researchers at the university of california–berkeley and michigan state led by food science professor leonard bjeldanes found that the diindolylmethane compound can aid in the prevention of cancer and activate the immune system to prevent viruses.
This compound is found in brassica vegetables such as broccoli and cabbage. cornell scientist rui hai lius research on nutrient combinations indicates that although an apple may only contain 6 mg of vitamin c it has enough additional antioxidants to produce as much antioxidant activity as 1 500 mg of vitamin c taken alone. tomatoes contain a phytonutrient called lycopene that correlates with a lower risk of prostate cancer. so what we already know and what we are discovering every day points toward the benefits of including more whole foods in our diet. a partial listing of the foods that make mateljans top 100 are: vegetables: broccoli spinach carrots fruits: strawberries cantaloupe oranges grapes tomatoes fish: tuna salmon shrimp nutrient-rich foods 139 nuts and seeds: sunflower seeds flax seeds almonds meat: calfs liver beef grass-fed lamb chicken beans/legumes: lentils lima beans tofu dairy/eggs: eggs yogurt low-fat milk grains: oats brown rice herbs: parsley mustard matjelan recommends and we concur lightly steaming or healthy saute´ing more of these foods using chicken or vegetable broth.
Remember highly processed or overcooked foods lose much of their nutrients and thus have less value for us. in the next section you will learn that some processed foods can even work directly against us based on the glycemic index. glycemic index the glycemic index gi is a measure of how quickly blood glucose rises after we eat carbohydrates. carbohydrates are converted to glucose which powers our muscles and our brains. some simple carbohydrates like sugar are absorbed quickly into our bloodstream causing glucose levels to shoot up. other complex carbohydrates like whole grains are absorbed more slowly and evenly. to calculate the gi of a food blood glucose levels are measured at 30-minute intervals for two hours after the ingestion of 50 grams of a particular carbohydrate. scores range up to 100 which is pure sugar.
Here are the gi scores of common foods: high-gi foods white bread bagels nonwheat doughnuts cookies candy sugar honey fructose corn syrup white rice 140 nutrition medium-gi foods brown and long-grain rice whole-grain bread and cereal pasta baked potato many fruits low-gi foods lentils most beans apples bran millet peanuts barley gi and energy when you provide your muscles and brain with a steady even supply of energy about 2 calories per minute you are able to exercise longer work more efficiently and stay alert. this is what medium-gi foods deliver to your system. because the flow of converted glucose is a consistent stream you wont experience a dramatic dip in your energy or ability to concentrate. high-gi foods in contrast give you a dramatic boost as large amounts of glucose enter your bloodstream more quickly. however high amounts of blood glucose also trigger a reaction from our pancreas: the production of insulin. short term the effect of insulin is to remove glucose from our blood which is why a sugar high may last only 20 or 30 minutes. that is why when you opt for a high-gi snack you get a temporary boost but also set yourself up for a crash. consuming more medium-gi foods instead of high-gi foods can mean the difference between staying alert and engaged versus feeling fatigued and withdrawn at a meeting or conference. the steady energy glycemic index 141 delivered by the right foods can for example help you skillfully guide a difficult conversation to a positive resolution. but if your energy is depleted the same conversation might spiral downward. and of course most of us can remember and regret decisions that we made when we were overtired. a more long-term and damaging consequence of relying on too many high-gi foods is that your insulin production mechanism may become impaired.
Initially this can result in more of your food being deposited as fat; over time however it is a leading cause of obesity and diabetes. dont misunderstand; it is not practical or necessary to eliminate all high-gi foods but it is important to understand their impact. clearly for our executive stamina goals of maintaining energy and mental alertness a mixture of low- and medium-gi foods will deliver the steady flow 2 calories/ minute that we need. later we will discuss how this concept can be applied to breakfast including when to have it and midmorning/midafternoon snacks.