Written by Jesse. Posted in Coaching Thoughts

The main focus of Ironman training and racing is on the improvement of metabolic efficiency. Developing metabolic efficiency is nothing more than training the body to use aerobic energy systems at the highest paces/wattages possible. This is the least costly way to fuel the body during exercise. There is a great deal of debate around how best to develop this aerobic efficiency. I, as most, would argue that training at intensities right around aerobic threshold (AeT) is the most effective way to improve the body’s aerobic efficiency. But, a recent push makes the argument that dietary changes can impact these adaptations. To this end, it has been hypothesized that “starvation workouts” can help to promote efficiency. These are rides and/or runs where athletes essentially starve themselves, in an effort to force the body to use fat as its fuel source. For example, an athlete on a long aerobic ride of 3 to 4 hours would consume only water, throughout. In my opinion the research on this practice is very uncertain, and is accompanied by a great deal of potential detriments, none of which make it an acceptable risk. Some of these potential detriments include:

1) Starvation workouts can be extremely catabolic, as the body is forced to attack lean muscle mass in order to create carbohydrates for fuel. This process of neoglucogenesis is nightmarish for lower BMI athletes, who are already strength limited, and older athletes (females beyond the age of 45 and males older than 50), who by the nature of their age have difficulty maintaining lean muscle mass. This assault on the body disintegrates muscle mass, thus exacerbating an already problematic limiter. Furthermore, depriving the body of the fuel that it needs to train over long durations can set the stage for a compromised immune system, leading to missed training time due to illness.

2) I am a firm believer that athletes should avoid nutritionally limited workouts, at all costs. In essence, never ever bonk! Be it a typical training workout or race day, it should NEVER happen. Starvation workouts create an atmosphere primed for bonking. This means that your workout is likely to be limited by a lack of fuel, prior to the physical energy systems being appropriately trained or stressed. This is in direct conflict with the reason why we do all of this training, in the first place, and focus so much time and effort on effective recovery. The goal of any workout should be to promote an environment where the athlete can have better and better workouts, pushing previous limiters, thus increasing fitness. Too many sacrifices are made, on a day-to-day basis, aimed at improving our fitness and racing, to allow our efforts to be limited by that over which we have 100% control over.

3)At the Ironman distance, training the gut to be able to absorb the nutrients in their intended race fuel is part and parcel to effectively executing their race plan. This is especially so for those with high sweat rates. These athletes often experience races that are limited by nutrition, rather than a true display of their fitness. Starvation workouts do not provide the opportunity to train this very limiter….race nutrition! We end up seeing athletes who are forced to walk through a great deal of the marathon, because they have not trained their bodies to consume and process the calories that will be required to race effectively. Because each of our athletes is equipped with a personalized race fueling strategy, that is practiced every single day in training (I cannot begin to tell you how many Power Bars and Power Gels QT2ers consume throughout the year), QT2 continues to produce some of the fastest Ironman marathoners in the professional and age group ranks.

4) I often hear of athletes using these starvation workouts during the early season base phase of training, while simultaneously in the gym trying to build strength. The catabolic nature of these types of workouts mixes terribly with the anabolic atmosphere that should be created, through a well-developed weight-training program, to create a positive hormonal balance.

Ironman racing has a nice clean series of events, namely the swim, bike, and run, with overtones of race fueling throughout and within each. How well an athlete has fueled their race does not typically become apparent until the run. I have always believed that the best way to approach limiters, in triathlon, is to first deal with those that exist in series with one another. With this in mind, and knowing that an athlete’s inability to handle their race nutrition is what typically undermines their Ironman, I try to first focus on this limiter as it typically occurs earliest in the chain of events. It really does not do much good to focus on a limiter that occurs further down the line, since it may never have the opportunity to actually become a limiter on race day. An athlete’s metabolic efficiency, on the other hand, is typically a limiter that appears in parallel with most of his or her other limiters. The cases are rare that an athlete’s race will come to a screeching halt, due to poor metabolic efficiency. Therefore, not until we are 100% certain that an athlete does not have a nutritional limiter, should we begin to even consider any unorthodox ways of improving metabolic efficiency, that could even possibly undermine the athlete’s ability to consume and process appropriate race fuels.

But, if you absolutely insist upon incorporating starvation workouts into your training regimen, I recommend trying it no more than once a month, and not until you have full confidence in all aspects of your training, racing, and fueling. At this time, there simply has not been enough research performed, on the topic, for me to feel confident endorsing it to any of our athletes. As with anything else in life, whether or not to utilize starvation workouts is really a matter of risk versus reward. In my opinion, the possible benefits of these workouts simply do not outweigh the potential risks.

Jesse Kropelnicki is an elite/pro level triathlon coach who founded QT2 Systems, LLC; a leading provider of personal triathlon and run coaching, as well as a leading provider of sports nutrition. He is the triathlon coach of professional athletes Caitlin Snow, Dede Griesbauer, Ethan Brown, and Tim Snow among others; and nutrition/cardio advisor for professional UFC fighter Kenny Florian. His interests lie in coaching professional triathletes using quantitative training and nutrition protocols. You can track his other coaching comments/ideas via his blog at