1 00:00:02,340 --> 00:00:06,323 What happens when energy is imbalanced? Well, we'll either lose weight or we'll 2 00:00:06,323 --> 00:00:09,211 gain weight. In this lesson, we'll talk a little more 3 00:00:09,211 --> 00:00:13,814 about this idea, and also discuss some specifics about body composition. 4 00:00:13,814 --> 00:00:18,38 As we talked about earlier, when we're not in energy balance, we'll see changes 5 00:00:18,38 --> 00:00:22,224 in body weight. If we're at equilibrium, we'll maintain 6 00:00:22,224 --> 00:00:25,800 our body weight. Another way to assess body weight is 7 00:00:25,800 --> 00:00:29,759 through BMI, body mass index. This was originally developed for 8 00:00:29,759 --> 00:00:33,125 clinical use, not for the general public but it is now used by people to evaluate 9 00:00:33,125 --> 00:00:37,78 their weight. BMI is specifically equal to weight in 10 00:00:37,78 --> 00:00:40,660 kilograms divided by height in meters squared. 11 00:00:40,660 --> 00:00:45,300 We have a range of values that we can use to assess someone's weight. 12 00:00:45,300 --> 00:00:53,490 A BMI less than 19 kg/m^2 is underweight. Normal ranges from 19 up to 25. 13 00:00:53,490 --> 00:00:59,340 Overweight from 25 to 30. And 30 and over is obese. 14 00:00:59,340 --> 00:01:02,502 In order to assess body weight, first we need to know how much we weigh. 15 00:01:02,502 --> 00:01:06,272 Weigh, we do that with a scale, and then we can use that and compare to height and 16 00:01:06,272 --> 00:01:10,737 other factors to evaluate it. The simplest tool is the weight per 17 00:01:10,737 --> 00:01:13,802 height table. This is a standard reference and can give 18 00:01:13,802 --> 00:01:17,593 a healthy weight range. What this allows for is some error. 19 00:01:17,593 --> 00:01:20,956 We're not going to give someone a specific weight they need, because they 20 00:01:20,956 --> 00:01:24,604 may have a larger bone structure, they may have more muscle mass, and this can 21 00:01:24,604 --> 00:01:29,490 vary how much they're going to weigh at a certain height. 22 00:01:29,490 --> 00:01:34,201 Here's a sample calculation. Try it yourself and then go ahead and do 23 00:01:34,201 --> 00:01:39,933 your own BMI calculation. Now BMI can be a little bit deceiving its 24 00:01:39,933 --> 00:01:45,937 only concerned with height and weight. Muscles weighs more than fat so a very 25 00:01:45,937 --> 00:01:51,553 muscular person may weigh more even though they're not actually overweight. 26 00:01:51,553 --> 00:01:55,969 BMI doesn't take this into consideration so very muscular people usually qualify 27 00:01:55,969 --> 00:01:59,145 as obese. Take this guy in the picture. 28 00:01:59,145 --> 00:02:05,147 He's 6 foot Three, weighs 245 pounds. His BMI is 30, but would you call him 29 00:02:05,147 --> 00:02:09,18 obese? You might not like the buff type, but he 30 00:02:09,18 --> 00:02:14,601 certainly would not be considered obese. Since you've learned a little bit about 31 00:02:14,601 --> 00:02:18,730 how energy is generated, let's talk about where that energy goes. 32 00:02:18,730 --> 00:02:24,470 How you use it and how we can balance our energy intake and output. 33 00:02:24,470 --> 00:02:28,335 Energy balance is quite simple its energy in versus energy out. 34 00:02:28,335 --> 00:02:31,530 If they're equal, you're in equilibrium, you're in balance. 35 00:02:31,530 --> 00:02:35,170 Think about it like this, when the work coming in is larger than the work you're 36 00:02:35,170 --> 00:02:39,800 putting out, you're going to have a big stack of work next to you. 37 00:02:39,800 --> 00:02:42,750 But if you can manage to keep up with that workload, you won't see a stack 38 00:02:42,750 --> 00:02:45,428 build up. The same thing can happen with our 39 00:02:45,428 --> 00:02:47,840 bodies. If we're not able to put out enough 40 00:02:47,840 --> 00:02:51,235 energy that energy builds up in the form of fat. 41 00:02:51,235 --> 00:02:55,129 So in terms of energy balance we can either be in equilibrium, positive 42 00:02:55,129 --> 00:02:59,485 balance where we'll experience weight gain, or negative balance, where we'll 43 00:02:59,485 --> 00:03:04,651 experience weight loss. When we talk about our desire to eat, or 44 00:03:04,651 --> 00:03:09,294 our need to eat, there's. Two terms we should consider, hunger and 45 00:03:09,294 --> 00:03:12,232 appetite. When I refer to hunger I am referring to 46 00:03:12,232 --> 00:03:15,368 the physiological and when I refer to appetite I am referring to the 47 00:03:15,368 --> 00:03:20,465 psychological drive to eat. Hunger is controlled by hormones and your 48 00:03:20,465 --> 00:03:24,86 nervous system. Based on chemical triggers the brain to 49 00:03:24,86 --> 00:03:28,80 tell you, I'm hungry, I'm full, I am not hungry yet. 50 00:03:28,80 --> 00:03:32,45 Various triggers send these signals including the presence or the absence of 51 00:03:32,45 --> 00:03:35,964 nutrients in your stomach and your body as a whole. 52 00:03:35,964 --> 00:03:39,932 The size and the composition of the the last meal can influence how quickly we 53 00:03:39,932 --> 00:03:43,936 get hungry again later. We have more fiber in our meals for 54 00:03:43,936 --> 00:03:47,641 example, it'll take longer to digest that, empty our stomach, so there'll be a 55 00:03:47,641 --> 00:03:51,728 longer period of time before we get hungry again. 56 00:03:51,728 --> 00:03:54,781 Regular eating patterns can also influence this. 57 00:03:54,781 --> 00:03:59,112 We will see that if you eat breakfast every morning, you wake up hungry. 58 00:03:59,112 --> 00:04:02,708 You eat lunch at a certain time every single day, you get hungry at that time 59 00:04:02,708 --> 00:04:06,122 of day. Your body can settle into this pattern at 60 00:04:06,122 --> 00:04:11,148 a hormonal and nervous system level. Environment and activity level can also 61 00:04:11,148 --> 00:04:15,698 influence, if it's cold, we need more kilocalories, so we'll be hungrier, and 62 00:04:15,698 --> 00:04:21,565 if we're active, we'll see the same. Hormones can also stimulate hunger; as 63 00:04:21,565 --> 00:04:26,209 hormones fluctuate in both men and women, we see alterations in hunger. 64 00:04:26,209 --> 00:04:30,153 And health, if we're sick, we may either feel more hungry or less hungry depending 65 00:04:30,153 --> 00:04:35,386 on what happens to these hormonal signals due to the illness that we have. 66 00:04:35,386 --> 00:04:39,846 The feeling of satiation will signal to your brain to stop eating. 67 00:04:39,846 --> 00:04:44,134 develops during a meal, while you are eating you can actually eat fast enough 68 00:04:44,134 --> 00:04:48,489 that you beat the signal so you devour everything on your plate, and then later 69 00:04:48,489 --> 00:04:55,436 you realize I am full or I am over full . This is why its good eat slowly to allow 70 00:04:55,436 --> 00:05:01,20 time for the signal to get to your brain. Energy density You have a meal can 71 00:05:01,20 --> 00:05:05,175 influence how quickly we might feel satiation. 72 00:05:05,175 --> 00:05:08,927 Foods that are energy dense are actually less satiating then foods that are high 73 00:05:08,927 --> 00:05:12,393 in fiber. Remember, it's the stomach distension 74 00:05:12,393 --> 00:05:15,505 that's at play. So, if I eat a handful of peanuts or a 75 00:05:15,505 --> 00:05:19,755 handful of popcorn, the popcorn's going to satiate me more. 76 00:05:19,755 --> 00:05:23,830 More and actually be lower in calories than the peanuts. 77 00:05:23,830 --> 00:05:28,587 Once we've experienced satiation, and until we experience hunger again, we are 78 00:05:28,587 --> 00:05:33,117 experiencing satiety. So satiety occurs between meals. 79 00:05:33,117 --> 00:05:37,472 It's the signal that says, you don't need to start eating again yet, we don't need 80 00:05:37,472 --> 00:05:41,591 nutrients. It's influenced by nutrient metabolism, 81 00:05:41,591 --> 00:05:45,147 and again, both the hormonal and[INAUDIBLE]. 82 00:05:45,147 --> 00:05:49,245 Nervous system level. This differs from appetite. 83 00:05:49,245 --> 00:05:53,535 You may eat a meal, and have an appetite for something, but that doesn't mean you 84 00:05:53,535 --> 00:05:57,745 have a true hunger. You can override satiety by your 85 00:05:57,745 --> 00:06:02,365 appetite, by your psychological need, your cravings, your desire for dessert 86 00:06:02,365 --> 00:06:08,425 for example, after an adequate meal. Relative to psysiological hunger, 87 00:06:08,425 --> 00:06:12,730 psychological appetite. Can sometimes be harder to control. 88 00:06:12,730 --> 00:06:16,878 It's often food-specific, that craving for popcorn from movies that can occur in 89 00:06:16,878 --> 00:06:21,620 the absence of hunger, wanting that chocolate cake after a meal. 90 00:06:21,620 --> 00:06:25,829 And it can override signals of satiety. You had a nice lunch, and then you go to 91 00:06:25,829 --> 00:06:29,900 an early tailgate for some football, and even though you're not really hungry, you 92 00:06:29,900 --> 00:06:34,770 stand around munching at the food that's around you. 93 00:06:34,770 --> 00:06:38,245 Hunger signals are integrated at the level of the hypothalamus. 94 00:06:38,245 --> 00:06:43,315 Its here that we're sending signals from our stomach or our fat cells, and then 95 00:06:43,315 --> 00:06:48,775 triggering release of other hormones that then elicit a response, hunger or lack of 96 00:06:48,775 --> 00:06:53,895 hunger. The integration of signal and response 97 00:06:53,895 --> 00:06:57,985 also requires hormones. Hypo Thalamic hormones that release to 98 00:06:57,985 --> 00:07:02,612 stimulate reduce hunger include the orexigenic and anorexigenic. 99 00:07:02,612 --> 00:07:06,568 Anorexic is simply a term that means to lose appetite. 100 00:07:06,568 --> 00:07:11,594 Anorexia nervosa is a disorder. So, don't confuse that with a simple term 101 00:07:11,594 --> 00:07:15,332 anorexic. Anorexigenic is something that would 102 00:07:15,332 --> 00:07:19,930 generate a lack of hunger. Orexigenic is the opposite it's 103 00:07:19,930 --> 00:07:24,710 stimulating a need to eat. It is stimulating hunger. 104 00:07:24,710 --> 00:07:28,280 The release of hormones from the hypothalamus is triggered by. 105 00:07:28,280 --> 00:07:32,942 hormones in other parts of the body. This includes the GI tract hormones and 106 00:07:32,942 --> 00:07:36,653 adipose tissue. There are three hormones that we should 107 00:07:36,653 --> 00:07:41,735 know Ghrelin, Peptide YY and Leptin. The hormone Ghrelin makes us hungry and 108 00:07:41,735 --> 00:07:44,972 Peptide YY and Leptin make us less hungry. 109 00:07:44,972 --> 00:07:49,596 Ghrelin acts on the orexigenic hormones while Peptide YY inhibit the orexigenic 110 00:07:49,596 --> 00:07:53,504 hormones. Ghrelin stimulates orexigenic hormone 111 00:07:53,504 --> 00:07:57,645 release while. Peptide YY inhibit them. 112 00:07:57,645 --> 00:08:02,134 These are both produced by the GI tract. Leptin found in the adipose tissue 113 00:08:02,134 --> 00:08:07,642 stimulates the release of[UNKNOWN] hormones and simultaneously inhibits your 114 00:08:07,642 --> 00:08:12,805 oxygen requirements. So, Leptin is a very powerrul hunger 115 00:08:12,805 --> 00:08:17,245 reducer and Ghrelin is the primary hunger inducer. 116 00:08:17,245 --> 00:08:21,570 So we now had to measure energy intake. We know how to measure calories. 117 00:08:21,570 --> 00:08:25,104 We talked a little bit about what controls our desire to put those calories 118 00:08:25,104 --> 00:08:28,596 into our bodies. So let's move on to how we get rid of 119 00:08:28,596 --> 00:08:31,909 those calories, how we burn those calories. 120 00:08:31,909 --> 00:08:35,159 This is energy output. The primary component of our energy 121 00:08:35,159 --> 00:08:39,761 output is resting or basal metabolism. This is what we need to breathe, for our 122 00:08:39,761 --> 00:08:44,349 heart to beat, for cells to grow. When we're children, this is what we need 123 00:08:44,349 --> 00:08:48,364 to get from infancy to adulthood. It is 60 to 75% of our energy 124 00:08:48,364 --> 00:08:52,354 expenditure. Now, there's some extreme conditions 125 00:08:52,354 --> 00:08:57,300 where other things can increase above basal metabolism. 126 00:08:57,300 --> 00:09:01,347 But that might be an example of the Olympic athlete, someone who is so 127 00:09:01,347 --> 00:09:06,104 excessively active that their energy output with physical activity is greater 128 00:09:06,104 --> 00:09:12,554 than that for basal metabolism. But for most of us, even those of us that 129 00:09:12,554 --> 00:09:17,354 are athletes, basal metabolism is the most significant component of energy 130 00:09:17,354 --> 00:09:21,600 output. Resting metabolic rate, this basal 131 00:09:21,600 --> 00:09:26,950 metabolism rate Is measured in calories per unit time in both men and women. 132 00:09:26,950 --> 00:09:30,118 This could be calories per hour or calories per day. 133 00:09:30,118 --> 00:09:33,358 Many factors can influence resting metabolic rate. 134 00:09:33,358 --> 00:09:37,750 Factors that increase this include total body weight and surface area. 135 00:09:37,750 --> 00:09:40,817 If you weigh more or if you have more surface area. 136 00:09:40,817 --> 00:09:44,525 You will have a higher metabolic rate. Hot and cold temperature. 137 00:09:44,525 --> 00:09:48,551 If it's cold outside or if it's very hot outside, your body needs to regulate its 138 00:09:48,551 --> 00:09:52,760 own internal temperature and that takes more calories, that increases metabolic 139 00:09:52,760 --> 00:09:56,854 rate. Fever will increase metabolic rate, 140 00:09:56,854 --> 00:10:01,599 hyperthyroidism, the overactivity of the thyroid gland, stress, caffeine, smoking, 141 00:10:01,599 --> 00:10:05,820 muscle mass. Muscle is what burns calories, not fat. 142 00:10:05,820 --> 00:10:09,596 So the more muscle mass you have, the higher your resting metabolic rate will 143 00:10:09,596 --> 00:10:12,820 be. This means you exercise and build muscle, 144 00:10:12,820 --> 00:10:17,930 even when you're sitting watching television you're burning more calories. 145 00:10:17,930 --> 00:10:22,340 Rapid growth, during young age and adolescence we see big growth spikes. 146 00:10:22,340 --> 00:10:26,525 During that period time Time, resting metabolic rate goes up. 147 00:10:26,525 --> 00:10:29,145 Pregnancy and lactation. That's pretty obvious. 148 00:10:29,145 --> 00:10:32,630 There's a baby growing inside. Our metabolic rate goes up, because we're 149 00:10:32,630 --> 00:10:36,965 needing to nourish that child. When we're lactating, we're generating a 150 00:10:36,965 --> 00:10:39,410 product. We need to be able to produce milk for 151 00:10:39,410 --> 00:10:42,305 the baby. And therefore, we increase metabolic 152 00:10:42,305 --> 00:10:44,712 rate. Doctors that decrease metabolic rate 153 00:10:44,712 --> 00:10:47,730 include aging as we get older. It just goes down. 154 00:10:47,730 --> 00:10:51,473 The female gender, women do tend. tend to burn less calories than men. 155 00:10:51,473 --> 00:10:55,69 fasting and starvation, even when we're sleeping it decreases a bit, if we 156 00:10:55,69 --> 00:10:58,781 continually fast, if we continually starve ourself our body goes into panic 157 00:10:58,781 --> 00:11:02,442 mode. It's worried that we're not going to get 158 00:11:02,442 --> 00:11:07,435 food, so it's going to reduce the resting metabolic rate, for survival purpose. 159 00:11:07,435 --> 00:11:12,685 Hypothyroidism, the underactive thyroid gland, And related to that fasting part, 160 00:11:12,685 --> 00:11:15,810 sleep. Not only are you not eating, but your 161 00:11:15,810 --> 00:11:19,926 entire body system is slowing down, it's in the rest state. 162 00:11:19,926 --> 00:11:23,124 Between these two lie genetics and medication. 163 00:11:23,124 --> 00:11:27,648 These can either increase or decrease your resting metabolic rate. 164 00:11:27,648 --> 00:11:31,850 The next component of energy output is physical activity. 165 00:11:31,850 --> 00:11:34,660 This is the second largest component technically . 166 00:11:34,660 --> 00:11:37,288 This is the energy we need for activity beyond rest. 167 00:11:37,288 --> 00:11:40,872 So, this means walking toward car region, going upstairs, walking round our 168 00:11:40,872 --> 00:11:44,512 building, going for a walk, going for a run, biking, hiking, working out at the 169 00:11:44,512 --> 00:11:49,298 gym, all of these things. And this can account for 15 to 30% of 170 00:11:49,298 --> 00:11:52,294 expenditure. This is highly variable value. 171 00:11:52,294 --> 00:11:55,527 You can imagine there will be a difference between someone who just walks 172 00:11:55,527 --> 00:11:58,822 around their home and someone who is an athlete. 173 00:11:58,822 --> 00:12:03,437 Now thinking about percentage though, the athlete, most likely have a higher 174 00:12:03,437 --> 00:12:08,205 percentage of muscle. Since muscle increases basal metabolic 175 00:12:08,205 --> 00:12:12,825 rate, the athlete's basal metabolic rate's greater than the person who's just 176 00:12:12,825 --> 00:12:18,163 walking around their home. And so still, relative to one another, we 177 00:12:18,163 --> 00:12:22,719 see a similar relationship between the amount that basal metabolism takes up and 178 00:12:22,719 --> 00:12:28,209 the amount of energy output that physical activity takes up. 179 00:12:28,209 --> 00:12:33,360 The final component of energy output is the thermic effect of food. 180 00:12:33,360 --> 00:12:36,130 May not realize but you do generate heat when you eat. 181 00:12:36,130 --> 00:12:40,718 Some people do more than others and this can range from about 5 to 10% of your 182 00:12:40,718 --> 00:12:46,368 total energy expenditure. So estimated energy requirement is some 183 00:12:46,368 --> 00:12:50,491 value you get. We're predicting the amount of energy, 184 00:12:50,491 --> 00:12:55,691 the amount of calories needed to maintain balance or equilibrium in a healthy 185 00:12:55,691 --> 00:12:59,532 adult. EER is based on data from doubly labeled 186 00:12:59,532 --> 00:13:04,165 water method that That isomptope method. And we'll estimate total energy 187 00:13:04,165 --> 00:13:08,922 expenditure with considerations for age, gender, height, weight and physical 188 00:13:08,922 --> 00:13:13,238 activity level. These equations we're going to go over 189 00:13:13,238 --> 00:13:19,18 don't apply to growth periods or for people that are significantly overweight. 190 00:13:19,18 --> 00:13:22,610 So let's go ahead and calculate total energy expenditure. 191 00:13:22,610 --> 00:13:27,138 Here's the equation. TEE, total energy expenditure equals REE, 192 00:13:27,138 --> 00:13:32,364 resting energy expenditure, plus PA, physical activity, plus TEF, the thermic 193 00:13:32,364 --> 00:13:37,852 effect of food. To estimate resting energy Expenditure. 194 00:13:37,852 --> 00:13:41,774 We use a value of one kilocalorie per kilogram per hour for men. 195 00:13:41,774 --> 00:13:45,622 And 0.9 kilocalories per kilogram per hour for the women. 196 00:13:45,622 --> 00:13:50,284 Therefore, calculations with males will be easier than that with women. 197 00:13:50,284 --> 00:13:54,872 You're just going to use a factor of one. Next comes physical activity. 198 00:13:54,872 --> 00:13:58,948 We have ranges that we can use here. If I were to ask to a calculation I would 199 00:13:58,948 --> 00:14:02,486 actually give you a specific number, not just expect you to memorize what 200 00:14:02,486 --> 00:14:07,663 moderate, light, or heavy is. The exceptional down there, that's the 201 00:14:07,663 --> 00:14:12,254 Olympic athlete that I referred to. There we can actually see potentially 202 00:14:12,254 --> 00:14:16,731 that physical activity is greater than resting energy expenditure. 203 00:14:16,731 --> 00:14:20,551 Lastly, we have the thermic effect of food, which is 10% of the sum. 204 00:14:20,551 --> 00:14:24,479 On arresting energy expenditure and physical activity. 205 00:14:24,479 --> 00:14:28,249 So lets do a sample calculation of energy expenditure. 206 00:14:28,249 --> 00:14:32,660 Follow along with the next several slides and do the calculations yourself. 207 00:14:32,660 --> 00:14:40,423 Then practice more calculations using your own body weight, and activity level. 208 00:14:40,423 --> 00:14:48,431 And maybe that of a friend, stateroom or relative . 209 00:14:48,431 --> 00:15:04,663 That concludes the energy lecture. So I suggest you get up and go spend some 210 00:15:04,663 --> 00:15:07,896 now.