Cancer prevention: what is energy balance?

MD Anderson Cancer Center
Date: 02-18-13


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Lisa Garvin: Welcome to Cancer Newsline, a Podcast series from the University of Texas: MD Anderson Cancer Center. Cancer Newsline helps you stay current with the news on cancer research, diagnosis, treatment and prevention, providing the latest information on reducing your family's cancer risk. I'm your host Lisa Garvin. Today, we have two guests, Dr. Susan Schembre who is in the Department of Behavior of Science here at MD Anderson, and Dr. Carrie Daniel who is in the Department of Epidemiology. And our subject today is Energy Balance. So in a nutshell, what is energy balance?

Dr. Susan Schembre: Thank you Lisa for asking. Energy balance really is the idea of balancing the energy you take in with the energy you expend, or the energy intake side is reflecting basically all the food and beverages that are calorie-containing that we consume. On the energy expenditure side, it's reflecting the processes of the body to maintain normal function. It's also reflecting the metabolism of food. And in addition to that, it's physical activity. So when energy in or the calories you consumed equal the calories that you expend to those different processes including physical activity, you're in energy balance.

Lisa Garvin: This sounds to me like I grew up in the 60s and I remember counting calories, it kind of sounds like that. Is that what it's like Dr. Daniel or?

Dr. Carrie Daniel: Yes, so essentially, you know, energy balance doesn't care what types of food you're eating. It's how much that you're eating at the end of the day. And over a sustained period of time, if you eat more than you expend, the natural consequence is weight gain. And so the marker of long-term positive energy balance is obesity which is probably something a lot of people have a better understanding of than energy itself.

Lisa Garvin: How in our world, our fast-paced technology driven world, it must be really hard to achieve energy balance, I would think. Is it that difficult?

Dr. Carrie Daniel: It's true. I mean, we have a lot of--I mean Sue can talk more about this as well. We have a lot of options to eat. A lot of exciting things out there that we can consume. And then our day to day life, just in the type of society that we are, we spend most of our time sitting in front of a computer or a TV as opposed to getting up and moving around for most of us. So yes, it is quite a challenge, I would say.

Dr. Susan Schembre: That is a challenge, but also we have to keep in mind that the body in itself is built to regulate its body weight. And that it will protect itself from weight loss in a sense that starvation is not a feasible option for the body. However, it's less protective against weight gain. So there are these cues when you're eating, the feelings of hunger and fullness that are actually produced by the body that are meant to allow for energy balance, so that we don't have to count those calories. And then there are those feedback systems that will help us guide our eating in that sense. But you're absolutely right. In today's environment which is different from many, many years ago where feasting and famine were a problem, we have food cues all over the place. And research shows that those cues whether are not there externally presented to you by, you know, a food being left on table in your office or walking by a bakery and smelling the scent of a really nice crescent or a cake, or whether or not you have some sort of emotional connection to food when you're upset, you eat. You know, all of those things can override the body's natural ability to maintain its weight.

Lisa Garvin:Well, I think we've heard the old attitude that you really don't know you're full right away. I mean the body doesn't signal that your stomach is full until later. I mean after you stop eating, is that true? I mean, it seems like the signals might be subtle to people.

Dr. Carrie Daniel: They certainly can be saddle in a fact that, you know, the old attitude. I think 20 minutes is the number that we put on that time. Yes, it does take time for the body to recognize that it's consumed foods. But ultimately, the pace at which we move, how fast our eating and being on the go all the time can really affect that.

Lisa Garvin: Now why are we in a cancer center looking at energy balance, what's the thinking behind that?

Dr. Susan Schembre: Well, if you are a nonsmoker, obesity is the leading cause of cancer. So that's I think an important point for people to understand. So there's a lot of interest in diet and cancer is been a long-term interest of mine, and then it's sort of moving towards this whole diet approach just as opposed to looking at specific foods, recognizing that obesity is behind cancer risk and also associated with cancer survival is taking a whole diet approach to get people and the energy balance. So giving them options that such as choosing whole grains versus refined grains, eating more fruits and vegetables, eating more lean meats and fish as opposed to, say, red meat can not only help you achieve your energy balance but can also lower your risk with cancer. So I think that's kind of what some of the interest comes from is that if we address the obesity burden, we go upstream and look at diet and physical activity which is part of this energy balance equation, we're going to have a major impact on cancer risk and on cancer mortality or cancer death.

Lisa Garvin: What are typically the obesity-related cancers? I mean, I believe like breast is one, colon is another?

Dr. Susan Schembre: Right. And then, there are left are known ones such as renal cancer, esophageal adenocarcinoma which is one particular type of esophageal cancer, and endometrial cancer.

Dr. Carrie Daniel: Endometrial cancer happens to be the most--we have the most evidence of the association between obesity with endometrial cancer, so yeah.

Lisa Garvin: So how does one go about achieving energy balance? One thing I did see in my research, they say it was EER, Estimated Energy Requirements, can--let's talk about that. What does that mean and how do you find out what your EER is?

Dr. Carrie Daniel: Estimated energy requirements are away for us to estimate how many calories you actually need to consume. And it's based--it's a dietary recommendation for intakes. And basically what goes in to that equation are a simply some measures of your height and your weight and your gender, your age, and then your physical activity level. And that is typically the harder part to estimate, is the physical activity level because not many people understand what activity counts as being, you know, moderate or vigorous.

Lisa Garvin: And let's talk about that because what I saw was sedentary, moderate and active. And obviously, I don't think there's any standardized measure for saying this is moderate, this is active, is there or?

Dr. Carrie Daniel: There is. For research purposes, there's something called a metabolic equivalent of task or compendium of physical activities where different physical activities are assigned a numeric value that correlates with their intensity or how much energy you burn in a particular time period doing that activity. For example, we know that when you're doing yoga, for example, you're going to burn less calories than if you're running. And so there are actual numerical values that we use in research to do that as estimates. But essentially, the best recommendations that I've seen are simply to just sit less and to move more. Obviously, everybody has different activities that they gravitate to. I mean ultimately the best exercise routine is something that you can actually enjoy and sustain, and it doesn't necessary have to be this intentional exercise such as playing a sport or going to the gym and running on treadmill. It can mean simply, you know, parking your car further away and walking, walking to lunch instead of driving, or the funniest thing is driving to the gym and then running on a treadmill and not going anywhere. So I mean there are other ways to make physical activity part of your daily routine so that it doesn't seem to take up so much time and energy and thought.

Lisa Garvin: I think there's been a lot of focus on the BMI or Body Mass Indexes as a measure of, you know, physical health and whether or not you're obese. But there seems to be some studies that's saying it's not maybe the best way to measure your overall health, is that true?

Dr. Susan Schembre: BMI has historically been our easiest way to look at the height to weight ratio and how it's related to health. But when we're thinking about the link between obesity and cancer, it's really more about the amount of excess body fat we have and not necessarily our weight as a whole because our body weight is made up of lean tissue as well as excess body fat. And it's really the body fat that is driving the link with cancer. Specifically, the more body fat we have, the more inflammatory pathways are actually activated. And then also with increasing proportion of body fat, we have similarly increasing proportions of adipose-related or obesity-related hormones that are actually those producing the mechanisms that drive the development of cancer.

Lisa Garvin: How does one know other than looking in the mirror which is not a good guide as we know? How do you know you have excess body fat? How do you measure that and decide whether or not you need to attack that?

Dr. Susan Schembre: Well, I mean one of the main things to consider is this belly fat or stomach fat. And that can simply be measured by taking a circumference of your waist or if your pants are getting tighter, and you're not building stomach muscles. That, what we call this real fat or belly fat is actually what puts you at greatest risk and is associated with all these hormones and inflammatory conditions that actually drive tumor growth and drive the cancer process.

Lisa Garvin: Why is it easier for some people to seemingly effortlessly maintain energy balance where with others, it's a constant struggle?

Dr. Susan Schembre: That's a lot of my researches focus, is trying to understand some of the differences between those who find it relatively easy and those who have a hard time. And you mentioned earlier that we do have those type A personalities that are very strict and regimented about what they're eating, how much activity they're getting. But, you know, we also recognized that that's not the norm that we do have people that are relatively able to maintain their weight and even in this environment. Some of the fields of research that are interested and answering questions about that are in the neuroscience area. We're looking at how the brain or people's brain respond to even seeing images of food and whether or not there are maybe some underlying predispositions that maybe subconscious to people, you know, looking for ways to address some of those issues, identify them and then address them, and moving forward in trying to help people who do have a hard time identifying new strategies other than just being sure they eat less and move more. That can help them sustained their energy balance.

Lisa Garvin: But obviously, as people age, their metabolic rate is affected. So how do you adjust energy balance for age because it seems as your metabolic rate goes down, it gets harder and harder to maintain that balance.

Dr. Susan Schembre: I mean, again, I think it comes back to adjusting your intake and your expenditure while recognizing that age decreases the amount that you need to take in. I mean, would you not agree?

Dr. Carrie Daniel: Yeah, absolutely. And the idea of kind of listening to those body cues of hunger and fullness will adjust as those energy requirements change as you age. So paying particular attention, that's not something we've really talked a lot about in research or among--you know, to the public yet. We're still, you know, increasing our knowledge in that area and--before really making those recommendations. But when you ask the differences between, you know--or you watch people who eat who are lean versus heavier, they tend to stop sooner, they eat less. I mean all of that has to do with them responding to their internal cues of hunger and fullness. So that would--normally, we would expect that as energy requirements go down as we age that those little changes are also made in hunger and fullness to maintain that energy balance.

Lisa Garvin: If we were to craft the primer for energy balance for the general public in how they can achieve that, where do they start?

Dr. Carrie Daniel: Generally, we're not throwing out any of the old messages. We know we want to continue to be mindful about the foods that we're choosing, making them less refined or last processed and more--of the whole food approach, might choose foods that are less energy dense but still provide the nutrients. So, you know, the processed foods are often empty foods, empty calories, getting away from those empty calories are one way to continue to have a diet that's enjoyable and healthy without feeling overly restricted.

Lisa Garvin: To me, energy balance sounds like portion size and calorie counting, am I far off?

Dr. Carrie Daniel: But I think what Sue and I are both tying to say is you don't necessarily have to sit with your piece of paper or your phone app and count calories, although that's one way to start to get people to become more aware. Eat less, move more is one part of it, but also to stop and think about what you're doing, what you're eating. We do a lot of eating that's not exactly mindful eating.

Dr. Susan Schembre:Right, right.

Lisa Garvin: And let's talk about your research avenues. Dr. Daniel, what sort of research are you doing in this area?

Dr. Carrie Daniel: So I'm nutritional epidemiologist. And so, my primary research has been looking at the role of diet and cancer ideology, so not only looking at a specific food such a lot of research with meat and cancer risk, for example. But also going back to that whole diet approach, what types of dietary patterns are associated with cancer risk. And behind that comes an energy balance as intake as a whole. I'm also interested in looking at specific cancers that are linked to chronic disease where obesity is upstream, if many else, chronic diseases such as hypertension and type II diabetes. So when you take into account obesity and the risk of these chronic diseases, your risk of cancer actually multiplies essentially. Because now, a person who has excess body weight and [inaudible] is really at increase risk of cancer, and also tends to respond poorly to treatment and has a greater risk of cancer mortality.

Lisa Garvin:And Dr. Schembre, what sort of research avenues are you exploring?

Dr. Susan Schembre: Well, I am academically and professionally trained as a registered dietician. And so, I often think about diet and how it's related to energy balance and obesity. But more specifically, I enjoy the side of research where we're looking at why we eat and how we eat, or why we eat so much. So I kind of always joked at for me it's more about why we eat versus what we eat when it comes to energy balance and current disease and cancer risk. My whole goal really is just to come up with some new messages to provide to the public regarding energy balance and how to go about doing that. Like I said earlier, we're not throwing away the idea of eating more healthy and then be more active, but we want to also add to that that awareness piece, becoming more aware, understanding that some of the triggers around eating behaviors or patterns of eating that could promote obesity, and then figuring out strategies which we can teach people to help them maintain healthy body weight.

Lisa Garvin: Any closing message?

Dr. Carrie Daniel: I would just say that from a clinical perspective, when going to the physician and the physician tells you, "You need to lose some weight," or something like that, that we--you know, rather than just sort treating a lot of these conditions like type II diabetes, hypertension, all goes back to obesity and behind that is the diet and the physical activity. And so, it would be nice if physicians would sort of get behind us public health folks and support us in that arena when they're are meeting with their patients, not only people who are otherwise healthy, but also people with cancer to let them know that it's not too late that even if you've been diagnosed with cancer, this is still the time to change your diet and lifestyle to have a better outcome in the end, better quality of life, better survival.

Lisa Garvin: So thank you both for being with me today. Some interesting thoughts in energy balance. If you have questions about anything you've heard today on Cancer Newsline, contact Ask MD Anderson at 1-877-MDA-6789 or online at [Background Music] Thank you for listening to this episode of Cancer Newsline. Tune-in for the next Podcast in our series.

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