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by Alan McCubbin
November 14, 2011
A few months back I wrote about weight loss for cyclists, for those trying to shed some unwanted kilos. But there’s also a group of cyclists who always struggle to gain weight, or those cyclists (and coaches) who become obsessed with weight loss at all costs. This raises the question of how much weight can you lose, in terms of your performance, your health and your sanity.
Body composition of successful cyclists
It’s not rocket science that lighter cyclists go faster up hills, and larger, more powerful cyclists make better time trial riders or sprinters. 1kg of weight loss is worth about 6 seconds in a 40km time trial (completed in 48 minutes on a dead flat course), but with a constant uphill gradient of 5% the difference would blow out to 55 seconds.
Power-to-weight ratio is king when the road heads uphill, and the top climbers are all pretty tiny. The majority are very short, giving them an instant weight advantage. But there are some exceptions like Andy Schleck, who weighs in around 65kg despite being over 6 foot tall. The PROs recently had a beach party in the Caribbean, and the sight of Frank and Andy with their shirts off must leave the locals wondering why the horse jockeys are so tall in Europe.
Improving power-to-weight ratio
Which way is easiest to improve power-to-weight ratio? Increase the power or reduce the weight? A study of club level cyclists, triathletes and mountain bikers was conducted over 10 weeks, where participants either included 2 extra sprint interval sessions a week, or a weight loss diet throughout. At the end of the 10 weeks both groups improved peak and anaerobic power-to-weight ratios, but neither method (or a combination of the two) proved to be a superior approach.
At the elite level of however there’s far less scope for large improvements in power output after years of training and racing – in this case weight loss will be a more effective strategy. Riders and coaches know this, and weird and wonderful weight loss targets and diets result. But for racing at club level, you don’t necessarily need to look emaciated to enhance your climbing prowess – a bit more quality training it seems will do the job.
How low can you go?
I often get clients who are already fairly lean ask me “how low can I go?”. There will always come a point where there’s not much fat left to lose, where you’re faced with the choice of either sacrificing muscle (and potentially absolute power) or accepting the weight that you’re at.
There’s no magic figure you can put on this but the use of skinfolds, a BodPod or DEXA scan can give you an idea of where you’re at and how much scope you’ve got to further lose body fat. Skinfolds are usually measured as a Sum of 7 (literally seven sites are measured and added together). We tend not to convert the result (in mm) into percentage body fat, because it requires the use of predictive equations that dilute the accuracy of the measurement. Generally speaking a Sum of 7 skinfold result of around 30-35mm is as low as you’d want to go (for men) before your run in to health or performance problems. For women it’s a bit more variable, but usually around 40-50mm. If you use a BodPod or DEXA then you’ll have results in percentage body fat. Even elite athletes will struggle to maintain a body fat of less than 5% for any period of time, and typically sit at around 6-12% for men and 13-20% for women.
Performance & health consequences of being too lean
In terms of performance, the most obvious consequence can be a loss of muscle mass (and therefore power). You might have a great power-to-weight ratio for that big climb, but has it been at the expense of your ability to ride crits, time trials or sprint?
But things can get more serious. The kind of dietary restrictions and/or massive training loads imposed by some cyclists and coaches can result in difficulty performing in high intensity sessions, and in more extreme cases overtraining, a state of ongoing fatigue which can take months to recover from. From a nutritional perspective it’s the lack of both total energy (kilojoules or calories) and carbohydrate compared to needs which can cause these problems.
There can also be health consequences of overtraining and undereating. The term “energy availability” describes the energy from food that the body can use for its normal functions, once the energy cost of exercise is accounted for. Large training volumes or very restricted dietary intakes (or both) can result in low energy availability – meaning that your body needs to decide how to ration out the available (but inadequate) calories. In order to protect vital functions the body firstly downgrades reproductive function to conserve energy, reducing your metabolic rate to prevent further weight loss. In women the result is a reduction in oestrogen production, and in men testosterone. It’s particularly obvious in women because it can lead to the absence or abnormality of menstruation. Unfortunately many female athletes don’t realise that this any cause for concern, some even think of it as a benefit. But before you tune out fellas, the effects of low energy availability apply to you too, there’s just no obvious sign that it’s happening.
The flow on effects of reduced oestrogen and testosterone are more serious. The main consequence is a loss of bone density, which increases the risk of stress fractures. Or if left untreated for several years, potentially osteoporosis later in life. We know that cyclists are already at risk of poor bone density and this may be one of the reasons. I’m not sure whether the PRO teams regularly monitor the bones of their riders, but the science suggests that perhaps they should.
Finally, there’s evidence that poor energy availability not only effects reproductive function and bone health, but also the immune system. This shouldn’t come as a surprise to many cyclists, and you’ll probably know of lean or dieting riders who always seem to catch a cold or flu. But for some cyclists the problem can be far greater – I’ve had several clients who have ended up with glandular fever, putting them out of action for months, with a high chance of reoccurrence in the future.
Obsession with weight – the psychology of dieting
With a large focus on weight and body fat from cyclists and their coaches, there is of course a risk that things can get out of hand, and cyclists become obsessed with their eating, developing unhealthy and unhelpful eating behaviours. Whilst clinical eating disorders like anorexia and bulimia are probably not very common in cyclists, there are definitely riders at all levels with subclinical disordered eating. Only one study in the last five years has attempted to quantify this. It was conducted with a mixture of international, university and club level male cyclists in the US. 20% of the riders studied were suspected to have disordered eating based on their psychological screening results, but only 8% actually thought they had a problem. 50% believed that disordered eating was “somewhat common” in the sport.
Is it the athletes or the coaches fuelling this obsession? In my experience it can be either. I’ve worked with a very lean client whom I’ve spent years helping to increase skinfolds to stay healthy, only for a team coach to forcibly restrict his eating on training camps fearing that he would get fat because he eats so much. This client was constantly starving, and resorted to sneaking boxes of cereal and muesli bars into his bag, scoffing it down at 3 in the morning. He still lost much of the weight he’d tried so hard to gain, and performances were terrible throughout the trip. But equally I’ve seen athletes obsessed with losing every last kilo, and concerned coaches and parents coming to me for help.
Reducing excess body fat will make you a faster cyclist, and reducing total body weight will especially help on the climbs. Many cyclists have plenty of scope to reduce body fat, and will reap the rewards when they race. But there’s always a limit to how lean you can be, and excessive weight loss or dietary restriction can have some nasty consequences.
It can often be a fine line between optimising performance and maintaining optimal health in sports where leanness is an advantage, particularly at the elite level. If you’re a female and have oligomenorrhea (irregular or inconsistent menstrual cycles of 36-90 days in length) or amenorrhea (complete absence of menstruation) in the absence of a medical condition, then it’s important to realise that this is not normal. A sports physician would be the first port of call, along with a sports dietitian who has experience working with energy restricted athletes. For blokes that struggle to gain weight, feel they have to restrict their diet heavily to meet their goals, or just feel like they’re struggling to have the energy to train properly, it’s also worth seeking professional advice.
But above all for the non-professional cyclist, don’t feel that you have to look like Frank or Andy to get better on the hills. A bit of specific, quality training can go a long way at club level. Being extremely lean is necessary for a career in PRO cycling, and they accept the health risks (knowingly or not) as part of their job. But if cycling isn’t putting food on your family’s table, at the end of the day is it really worth the risk to climb a little bit faster?