by Chad Kerksick PhD June 06, 2011 4 min read
A number of studies over the last several years have reported this outcome. However, people must realize that a majority of the studies illustrating this outcome has been performed on non-human animals. Creatures like rats, mice, rabbits and monkeys were the lab “rats” in these studies. Research in humans is slightly more complicated. Imagine being a researcher and telling one of your subjects they can’t have any beers or nachos at a baseball game or at the weekend cookout, they should only eat vegetables and take it easy on the dip while you’re at it. Having done a few studies in people myself where we ask them to adopt some behaviors, I’m thinking full compliance will go over about as well as a lead balloon.
Research at the prestigious Washington University in St. Louis, MO and at the University of California-San Francisco is not letting that stop them. When scientists at Washington University, one of the primary universities in the U.S. that has performed a number of studies on this topic, had human research subjects cut their caloric intake, they found a lower core body temperature when compared to non-restrictors. This finding was suggested by many to be a positive adaptation. Researchers in the San Francisco area are conducting the CRONA study, which stands for (Caloric Restriction with Optimal Nutrition and Aging), a large study which includes people from many different states and even a few different countries. Amazingly, this dietary practice has grown by leaps and bounds, with many people thinking that calorie restriction is the long-lost “fountain of youth”. While this work is fascinating and will provide meaningful information for people who do regularly restrict their calories, major questions still exist. The primary question that is being fleshed out is if a longer life equals a better life. Personally, I would be more interested if this research was showing that restricting calories actually improved the quality of life and if you ended up living longer then that would be icing on the cake. Currently, the research is too preliminary because even in the animal studies, clear conclusions don’t exist to explain how well the restricted animals are living. This means that we are even further away from having decent evidence in humans.
The next question would be, “how does this research fit into the lives of people who regularly exercise, watch their diet and consume dietary supplements to support their health and nutrition?” In a number of ways, millions of people follow this lifestyle for short periods of time to lose a few pounds, drop a dress size or two or just to get ready for the summer. The reality, however, for many people and I’ve written about this before is that some level of caloric restriction (along with an increase in calorie burning) is likely necessary just to balance out the ‘calories in vs. calories out’ argument. Remember this is just to get to where you are no longer gaining weight. A caloric restriction lifestyle means you cut back on dietary intake another 25% or so. If you are a woman who eats anywhere from 2,000 – 2,500 calories per day, this means you are restricting by an additional 500 – 625 calories each day. If you are a guy who eats a typical diet providing around 2,500 – 3,000 calories, this means cutting another 625 – 750 calories each day. Furthermore, if your goals are to try and add some muscle, this dietary habit is not going to be very compatible with that goal. As a matter of fact, it may result in a scenario where you actually burn off some protein, unless you do a good job of supplying multiple doses of the essential amino acids throughout the day (every 2-3 hours like clockwork…forever). For people who want to lose some fat, caloric restriction is nothing more than any other diet which restricts calorie intake. Nothing fancy, just the same old thing we’ve talked about before.
The possibility, however, that it may help you live longer is an intriguing outcome. When you consider that the last 30 – 40 years has been a pattern of too little exercise and too many calories consumed which has resulted in ever increasing levels of chronic disease such as obesity, cancer and diabetes an argument can be made that the practice will improve the quality of our health.
At the end of the day, research has shown in several different types of animals whose feeding and physical environment is completely controlled that restricting calories can extend life, but more work is needed to see if the health of these animals has improved and also if similar findings result in humans. We all know that caloric restriction helps to burn off some fat, increase our muscle tone and improve our body composition and for now that’s how it will remain. If it ends up helping me live longer AND better, then you can ask me to stay away from the queso and bacon cheeseburgers.