In
the past few years, dieting has become such an important part of society.
Society is addicted to losing weight, gaining muscle, attaining better health,
and trying to live longer. In Caloric restriction (CR), in the absence of
malnutrition, has shown to extend lifespan in many animal models and decrease
age-related oxidative stress in multiple tissues & organs 1. Furthermore, recent studies show CR extends the lifespan
and reduces a number of adverse effects associated with aging. The principal
theory on caloric restriction is a combination of “rate of living” and
“oxidative stress” theories, which emphasize the importance that metabolic rate
and reactive oxygen species have on lifespan 4. The ‘rate of living’ theory claims that the higher an
organism’s metabolism, the shorter its life span, thus explaining the effects
of caloric restriction on longevity 4. The ‘oxidative stress’ theory claims that caloric
restriction reduces oxidative stress, which in turn reduces damage to tissues
and organs (Figure 1) 3,4. Researchers in the caloric restriction field have examined
how age-related changes in physiological and endocrine systems play a role in
metabolic functions, which may be correlated with health and lifespan benefits 4.
 |
| Figure 1. CR enhances resting energy efficiency to decease systemic oxidative damage (3). |
An example
of ongoing work investing how CR may benefit overall health is a study by Redman
et al 2. Here,
it was hypothesized that maintaining patients on CR diets for a period of two
years would reduce energy expenditure (EE) of endocrine mediators and oxidative
stress in energetically active tissues 2. Finally, the authors
conducted this study to provide scientific validity for the biological aging
hypothesis; which explains that a prolonged use of CR diet enhances energy
efficiency, reduces reactive oxygen species, and reduces oxidative damage to
tissues and organs 3.
The
researchers recruited 53 people, of which only 19 people were assigned to the control group and 34 people
were randomized to the caloric restriction group 3. In order to see how CR plays a role the amount of
weight each group lost was examined 3. The CR group
lost about 9.4 kg on average and a 16.5% reduction in energy intake 3. In year two the CR group
only maintained their weight loss and had a 14.8% reduction in energy intake
(Figure 2) 3. The weight
loss in the CR group was primarily fat mass loss, but
some fat-free mass loss was observed as well 3. This study explains the idea that changes in metabolic
adaptation of energy expenditure show reductions in oxidative stress 3. This implies that metabolic adaptation may be related
to energy conservation, and in turn may delay biological aging, which in turn
enhance lifespan 3.
 |
| Figure 2. Calorie Restriction and Change in Body Composition. Percent of calorie restriction (A) achieved after 1 and 2 years of calorie restriction and the resulting change in fat mas (FM) and fat-free mass (FFM) (B). N=53: 34 CR, 19 controls. The p value for statistically significant treatment group effects, adjusted for multiple comparisons, is shown. The changes in weight, FM and FFM were all significantly different between the CR and control group (p<0.0001 for all, treatment main effect)(3). |
Oxidative
stress was measured to understand how the biological aging hypothesis. The
participants gave urine samples, which were used to measure urinary 2,3-dinor-iPF(2α)-II by liquid chromatography to see
oxidative stress 3. The urinary
F2-isoprostane excretion showed a significant reduction in the CR group but no changes in the control group 3. When analyzing the urinary data, it was found that urinary
2,3-dinor-iPF(2α)-II concentrations where significantly lower for the CR group
than the control group at year two 3. These changes in the urinary 2,3-dinor-iPF(2α)-II
concentration show a drop in oxidative stress, but these findings need to be
studied long-term 3.
Redman et
al, explain that patients who were put on a caloric restriction diet for two
years had an impact on biological aging 3. This study shows
that the use of CR does have some beneficial aspects to human life span due to
efficiency in energy metabolism, fat loss, and reducing systemic oxidative
stress. CR’s effectiveness is important as it indicates weight loss to be safe
and tolerable, as well as a reduction in systemic oxidative stress to live
longer. Overall, caloric restriction is important for people’s health, people’s
lifespan benefits, and allow people to live longer.
By Cocanut Suhail, a Master's of Medical
Science Student at the University of Kentucky
References:
1. Il’yasova,
D., Fontana, L., Bhapkar, M., Pieper, C., Spasojevic, I., Redman, L., Das,
S.K., Huffman, K., and Kraus, W. (2018). Effects of 2 years of caloric
restriction on oxidative status assessed by urinary F2-isoprostanes: The
CALERIE 2 randomized clinical trial. Aging Cell. 17: e127109.
2. Ravussin,
E., Redman, L., Rochon,J., Das, S.K., Fontana, L., Kraus, W., Romashkan,
S., Williamson, D., Meydani, S., Villareal, D.T., Smith, S., Stein, R., Scott, T.,
Stewart, T.,Saltzman, E., Klein, S., Bhapkar, M., Martin, C., Gilhooly,
Holloszy, J., Hadley, E., Roberts, S., and Kritchevsky, S. (2015). A
2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility
and Effects on Predictors of Health Span and Longevity, The Journals of
Gerontology: Series A. 70 (9), 1097–1104.
3. Redman,
L. M., Smith, S. R., Burton, J. H., Martin, C. K., Il'yasova, D., &
Ravussin, E. (2018). Metabolic slowing and reduced oxidative damage with
sustained caloric restriction support the rate of living and oxidative damage
theories of aging. Cell Metabolism. 27(4), 805-815.
4. Speakman,
J., and Mitchell, S. (2011). Caloric restriction. Molecular Aspects of
Medicine. 32: 159-221.
Great blog post! I think a lot of the diets do no go into the idea of caloric restriction and that there are a lot of misconceptions on reducing the daily caloric intake to see all of these benefits long term. Although research suggest it can potentially decrease the rate of aging at a cellular level, it has to start early on to see the greatest benefits later on. With this in mind, we must also see if patients who are experiencing weight gain with changes in lifestyle, diabetes, daily intake of more than 2000 calories should consider this highly under rated way of living. But the question is is it worth living a couple of extra years and sacrifice all of the foods we enjoy eating for the next 25 years?
ReplyDeleteI like your question but yeah that is something what we have to take into consideration. It would seem that living a few extra years along with better health outcome would be beneficial overall thou.
DeleteNice topic! I think focusing on how our diets can impact our overall health is something to be stressed in today's society, as it becomes easier to access high calorie junk food. It was interesting seeing the results of caloric restriction in a human trial. I would be interested to know what the diets of the people in the CR group consisted of and what their exercise levels were. I think many people are turned away from the idea of calorie restricting because it sounds like you have to eat a lot less or work out a lot more. Conveying the idea that you can restrict calories in ways other than eating the bare minimum would be helpful in encouraging people to explore calorie restriction, so knowing what the diets of the people from this trial were would be good information, as well.
ReplyDeleteCaloric restriction is definitely a hot topic in the current nutritional and gerontological literature. I have been hearing a lot about CR and I am a big believer in the current data which indicates that CR can improve longevity and overall wellness all across the board. Although it certainly needs to be researched much more extensively, CR could pave the way into developing supplemental mimetics that positively influence aging in a similar way as the diet itself. In addition to caloric restriction, I also am a proponent of intermittent fasting which is similarly a "hot-topic" of aging and fitness research. Overall, caloric restriction seems to be a hit, and it likely is paving the way for us to better understand and modulate the aging process.
ReplyDeleteGreat post!
Great topic! I appreciate your explanation on how this diet works. I hope people can distinguish the difference between having a calorie restricted diet and a complete fasting diet. A person should not think that going into a malnutrition diet is the best way of losing weight or fat. There should be an awareness between the boundaries of not eating a high calorie, fat, sodium, etc. diet than to simply not eating at all. Depriving the body of necessary nutrients does not make a person fit, it makes them more vulnerable to sickness and disease. Good job!
ReplyDelete“Calorie Restriction and Fasting Diets: What Do We Know?” National Institute on Aging, U.S. Department of Health and Human Services, www.nia.nih.gov/health/calorie-restriction-and-fasting-diets-what-do-we-know.
There are so many diets out there that claim success to weight loss, and yet many of these diets lack any substantial research. Certainly this does not stop your average human from wasting their time on the latest diet trends. I have been hearing more and more research on the benefits of caloric restriction and I am very interested to see how the research evolves. Likewise I would like to see how this research can be put into an appropriate perspective for those who many not understand the depths of the research. Most people are looking for the easy way out, and so the question becomes how could we get humans to follow through and remain consistent with a calorically restricted diet so that we may appreciate its full effects.
ReplyDeleteJen Eccleston
Caloric restriction is a very interesting topic. I personally think that using caloric restriction to produce a longer life is far into the future. But using caloric restriction to establish better health is of great importance. What was interesting to me was the fact that restricting calories didn’t produce a longer life but it produced a longer healthy life. As we age our bodies deteriorate and it becomes a burden for our families to take care of us. Using caloric restriction to limit that burden is something that has very promising effects. A very fascinating topic that I would love to learn more about!
ReplyDelete-Erin Harris
DeleteSuch an interesting topic! There have been so many 'suggested' diets which have been changing/evolving for years. I enjoyed your explanation of the diet and the study performed with it. I'm excited to see where further research with this diet can go and if any aging conditions could potentially benefit from this or a similar diet.
ReplyDeleteCaloric restriction is very interesting topic that is very relevant to today! Dieting is such a common route of weight loss and so many people need to understand what they are getting themselves into. Understanding the biochemical effects of altering your diet is very important. Helping people understand that it isn’t necessarily not eating, more so watching what and how much you eat is the key aspect. Having research to support these diets is very important and that’s where this blog post lies. Great work!
ReplyDeleteNutrition plays a major role in how we take care of our bodies and how we supply our bodies with the energy they need. I have read a lot of studies about caloric restriction in animals, but I was unsure how this could apply to humans. I love that you took a topic we discussed in class a step further to explain the benefits humans gain from caloric restriction. On the flip side of this, the general population would probably be devoid of even trying caloric restriction because the name itself indicates the challenge of eating fewer calories. Going forward, it would be beneficial to educate the public about the science behind a topic like this. Enabling patients to lose weight in a safer and more tolerable way is always a positive thing and living longer is not a bad side effect! I loved your topic and your blog post was well written. Great job!
ReplyDeleteEveryone wants a quick fix for aging, weight loss, living longer, etc...it seems as though, in most cases, a healthy diet can help all of these. Caloric restriction sounds daunting, but after reading about CR, self control is a big factor. When portions at restaurants are huge, everything is XL, it makes it difficult for people. I wish more people knew the science of it as you explained, it's very informative.
ReplyDeleteGreat post! There has been a lot of importance placed on diet and many aspects of life whether its disease, health, or lifespan. I remember during Dr. Pearson's lecture he had mentioned that caloric restriction in terms of affecting lifespan should be implemented early in life. I can't quite remember when he said it might be too late so I am curious if you came across anything that may have expressed that. Was it mentioned in the study you cited? Regardless, I think you make a compelling argument because there are so many benefits to decreasing your caloric intake. I appreciate that you not only explained what caloric restriction is but also included a study to support your argument. It is definitely eye-opening. I am excited to read and hear about more studies pertaining to this; I think it will help a lot of people. Good job!
ReplyDeleteCocanut, super interesting article! An ongoing debate among metabolism, obesity, and aging researchers is the question of whether a chronic deficit in energy intake leads to metabolic slowing or a decreased rate of living. Numerous factors, like antioxidant mechanisms and dietary and biological factors, play a role in metabolism. According to the rate of living theory, a slower metabolism is the most beneficial to healthy aging and that organisms that burn or utilize energy most efficiently should experience the greatest longevity. Findings from this two-year CR trial in healthy, non-obese humans, provides new evidence of persistent metabolic slowing accompanied by reduced oxidative stress, which supports the rate of living and oxidative damage theories of mammalian aging. As one of the first research studies that focused on investigating the effects of calorie restriction in humans, this was a huge step forward towards reliable answers to questions that have plagued aging researchers for years. The results of this clinical trial proved that decreasing individuals’ caloric intake by roughly fifteen percent over two years. The aging process slows as does metabolism, which further protects the participants from age-related diseases. The results of this study showed that CR lowered systemic oxidative stress. This is an important finding because an accumulation of systemic oxidative stress has been linked to age-related neurodegenerative diseases including Alzheimer’s disease and Parkinson’s disease, as well as, diabetes, cancer, and cardiovascular disease. A calorie restricted diet can decrease the rate of an individual’s basal metabolism, and if products of metabolic processes increase the rate of aging, then persistent adherence to a calorie-restricted diet over the course of several years can lower the risk of chronic disease and increase lifespan. Those participants in the calorie restriction group lost an average of roughly 9 kg, even though these individuals did not follow a specific diet and weight loss was not the goal of the study. No adverse effects, like anemia, excessive bone loss, or menstrual disorders were noted; in fact, both trials led to improvements in mood and health-related quality of life. This result indicates that healthy individuals that can also benefit from a CR diet.
ReplyDeleteInteresting! I really liked reading more about this topic after the lecture we had in class regarding this topic and aging. One nutritional alteration that I have always found really interesting is the idea of intermittent fasting. There are many forms of the diet that range in timespan from daily to several days of fasting each week or month. I think the idea of this is great to provide a reset to your metabolism. However, after your post, it has made me question if fasting over several days may actually be very detrimental to the metabolism. On the other side, fasting that occurs by fasting for 50% of the day could help to assist with the idea of caloric restriction. It’s hard for many people to follow a caloric limit on their own time. By using the idea of intermittent fasting each day, it could really help to ease the psychological difficulties that surround limiting food intake.
ReplyDeleteInteresting post. I really like the idea of using diet as an alternative to medicine. I know that many people are looking into drastic diets in order to improve their weight, and their health in general. It is good to see something that is actually scientifically supported. Here is something I found on alternate-day fasting. It is a different take on the idea of intermittent fasting. In this diet, a person would essentially only eat every other day. This study showed that subjects did have some rebound calories from not eating the previous day, but it still resulted in an overall caloric deficit, which lead to weight loss and improved general health markers over the 4 week period.
ReplyDeleteStekovic, Slaven, et al. “Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-Obese Humans.” Cell Metabolism, Cell Press, 27 Aug. 2019, https://www.sciencedirect.com/science/article/abs/pii/S1550413119304292?via=ihub.
Hey Cocanut, I thought your post was very interesting, mostly because of how hot-button the topic of caloric restriction is. I think that the results of CR studies in humans are pretty clear in regards to the benefit that it can confer, however it is not yet known whether lifespan for humans is meaningfully increased because no such long term studies have been done. In many animal models, overall health but not lifespan of animals are increased. If, in humans, longevity is not improved in all cases, is it still worthwhile to encourage or focus on CR diets? I think so, especially considering that this particular lifestyle alteration reduces risk for cancers, diabetes, and metabolic syndromes. The trick is really just convincing people to stop over-eating, a think that many people, myself included, enjoy doing.
ReplyDeleteI love caloric restriction research because it shows that CR can produce many benefits that are very valuable and extremely hard to come by through any other means. The reduction in oxidative stress is one of those rare benefits. Other than eating blueberries and other antioxidants, I don't think I've heard of anything that effectively decreases ROS in the body. I think that we still have much to learn about the benefits of caloric restriction, and I'd bet we'll uncover some more drawbacks as well. However, the way I like to view it is that the human species evolved in an atmosphere where food was never, or at the very least, rarely readily available, thus a (healthy) restricted energy state is far more natural to our body than one of chronic excess energy, so benefits that come from CR seem like they could be a sign that the body is more comfortable and efficient when reverted back to its "primal state", so to speak.
ReplyDeleteGreat Post! Data from human studies show that CR remains the foundation in the prevention and treatment of obesity and its numerous complications as well as a means to achieve longevity. Moderate CR achieved through intermittent fasting or restricting feeding in combination with regular physical activity exerts additional beneficial health effects even in non-obese individuals. There are numerous factors at play when it comes to one’s metabolic phenotype; that, then greatly affects your metabolic outcome. Can you handle a high protein low carb diet? How does your body respond to sugar? Are you genetically predisposed to heart disease and atherosclerosis? What stresses are you under, and how does that affect your gut-biome and subsequent metabolic outcome? How much physical activity should you couple with this diet to meet your expectations? These are all questions that can be addressed prior to beginning a diet and life-style change. However, I believe that research suggests the most effective dietary intervention to promote longevity in humans is calorie restriction. Great post overall! I think it is something that will inform longevity studies in the future.
ReplyDeleteIt's quite interesting how just the amount of calories you are putting into your body can alter your biochemical makeup in the way that the CR group had a significant decrease in leptin production in comparison to the control group. I think it is often forgotten how important food is to overall health. The biggest concern I have in this approach is how most of these studies have only been done on mice and the ones done on human don't outline the foods being ingested in the diet; nor do they take into account the varying caloric needs of each individual. While this is great in theory, I wonder how applicable it really is and while it may extend lifespan, how much does it really benefit your life? If it is so restricting that you can't have a social life or enjoy the offerings around you, is it worth the few years it may add if any?
ReplyDelete-Alivia Larkin