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A while ago I was inundated by a flood of vitriol from the public for suggesting that it is always a good idea to eat a light breakfast before doing exercise and then having another top-up carbohydrate meal after activity.
The adherents of exercising on an empty stomach were incensed. How could I make such a suggestion when everyone knows that one needs to "Train low and Compete high" to lose the maximum amount of weight?
Elite athletes
Well, my article was aimed at top athletes who are practically forced to rely on the glycogen stores in their muscles and liver to sustain their intensive efforts for hours on end. The logistics of ingesting very large quantities of carbohydrate to fuel their performance, thus make it important to use any chance (including breakfast) to eat some energy-boosting food, before, during and after exercise.
Unless an athlete is trying to "make weight" there is as yet no concrete proof that training without a carbo-boost has significant advantages for elite athletes.
Researchers in the field of sports nutrition are at present trying to rectify what Hawley and Burke (2010) describe as “this surprisingly sparse literature”, by doing more studies to investigate if "Training low and competing high" has any advantages for elite athletes.
Some of the studies are attempting to identify what happens on the cellular level when an elite athlete trains hard on what could be regarded as "an empty stomach".
Such knowledge can be valuable to athletes who are trying to increase their performance or endurance or shave a millisecond off their time.
However, to date combined analyses of the results of the relatively few studies in this field, have not found sound scientific proof that it is advantageous for top athletes to exercise in a carbohydrate-deprived state.
Non-elite athletes
According to Hawley and Burke (2010), the study that sparked the "low vs. high glycogen/carbohydrate" or "empty stomach vs. fed" debate and then coined the slogan “train low, compete high” was conducted by Hulston and his team of the School of Sport and Exercise Sciences at the University of Birmingham, UK, with 14 well-trained cyclists. The paper on the Birmingham findings was published in 2010 and the authors concluded that “Training with low muscle glycogen reduced training intensity and, in performance, was no more effective than training with high muscle glycogen. However, fat oxidation was increased after training with low muscle glycogen, which may have been due to the enhanced metabolic adaptations in skeletal muscle.” (Hulston et al, 2010). Understandably elite athletes who wish to increase their training intensity and performance, would probably not wish to follow this route.
But trainers trying to assist non-elite athletes to lose weight have latched on to these and other findings of the few studies that have been conducted in this field, and are now advising their clients to exercise on an empty stomach to achieve greater weight loss.
Practicalities
It is of course, up to every individual to choose what state they wish to exercise in - fed or starved - but if we consider that the majority of people who want to lose weight also have to function within the constraints of their daily lives, which require them to produce a full day’s work and attend to many other duties in addition to their exercise routine, then exercising in the starved state may well produce a slight increase in weight loss, but at the cost of overall daily performance due to exhaustion caused by energy depletion.
To achieve both increased weight loss via low training and to function optimally during the rest of the day, you would need to ensure that you have a proper breakfast after your training session. Given the hectic lives we lead, I doubt that the majority of slimmers will make provision for eating a well balanced, carbohydrate-rich meal on their way to, or at the office after skipping breakfast at home and rushing to the gym for an hour.
So where does this leave our aspiring slimmers? Washed-out and exhausted for the rest of the day? Will they then overeat at the next meal which happens to be lunch when that tempting snack trolley comes round or in the canteen where "slap" chips and pies beckon? A pie with a hearty serving of fat-laden chips is guaranteed to nullify that additional fat loss achieved in the early hours of the morning on an empty stomach.
So my advice for non-elite athletes who are using exercise to lose weight is still to have a light breakfast before they leave home (cereal and/or fruit with low-fat yoghurt and coffee) and a carbohydrate-rich, possibly low-GI snack when they get to work (e.g. Up and Go which has a GI of 46 is easy to take along). If you have adequate muscle and liver glycogen stores you will be able to exercise more intensely and also lose weight, but instead of tottering around in a hypoglycaemic trance till lunchtime, you will also be able to think more clearly and do your work more efficiently.
Interesting questions
Hawley and Burke (2010), who are among the leading researchers in the field of sports nutrition, analysed the "Train low, Compete high" study data that is presently available and have come up with the following questions that must still be answered before we can recommend this practice to all sportsmen and women, particularly our top athletes.
Hawley and Burke (2010) indicate that we need clarification of the following:
- The confusion that has been created by the “one-size-fits-all” theme which is being promoted to replace the “high-carbohydrate diet” in sport.
- Determining if exercising in the fasted state does really improve weightloss, in the light of the finding that “rates of fat oxidation during submaximal exercise [i.e. the type of exercise that most non-elite athletes do], were not altered” by exercising in the fasted state or 90 min after a carbohydrate-rich breakfast plus additional carbohydrate supplementation during exercise at the rate of 1 gram per kg body mass per hour.
- If ‘Train low, Compete high” will increase lean body mass (a desirable result during slimming) or result in a loss of lean body mass/muscle tissue.
- If the purported weight loss benefits of exercising in the fasted state will have negative effects on health, balanced dietary intake and performance parameters. There is a great deal of scientific evidence that supports the use of carbohydrates before, during and after exercise to sustain immune function and prevent susceptibility to infections, which are associated with very strenuous training. According to Hawley and Burke (2010), “Training with low carbohydrate availability also is likely to be associated with reduced immune function and expose the athlete to an increased risk of illness and/or injury.”
- If the finding that training-low makes athletes do less work because “they perceive the effort to be higher”, thus impairing overall achievement and performance.
Finally these authors point out that many elite athletes probably already "Train low" because of inadequate knowledge of nutrition and the difficulties associated with eating large quantities of carbohydrates before early morning training sessions, or because it is difficult to top up on carbohydrates during workouts in the gym or on the field (Hawley and Burke, 2010).
I am inclined to agree with Hawley and Burke (2010) that “before train-low strategies can be recommended, it seems important to investigate what occurs in the sports world and whether some athletes have already developed successful protocols via trial and error”.
They cite the example of African distance runners who train two to three times a day and often do so in the fasted state, but who tend to eat a basic diet that is higher in carbohydrates than athletes from other countries.
So for elite athletes the decision to "Train low, compete high" needs to be made in conjunction with your dietician, and non-elite athletes need to weigh up the overall demands of their lives, before they train on an empty stomach.
References
(Hawley JA, Burke LM, 2010. Carbohydrate availability and training adaptation: Effects on cell metabolism. Exercise & Sports Sciences Review, Vol 38, No 4. 152-60; Hulston CJ et al, 2010. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Medicine & Science in Sports & Exercise, Vol 42, No 11, 2046-55.)
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