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Loss of lean body mass, which is essentially muscle, drives your metabolic rate down and reduces your capacity for physical work. A successful fat-loss program centers on the reduction of body fat levels with minimal disruption to your metabolic rate and energy levels.
 
 
Energy Balance
That said, you’re only going to lose weight if you create a negative energy balance. This means quite simply that you must have less energy going in (calories from food) than you’re using up (basal metabolic rate + activity). If your energy in equals your energy out, you’re said to be at ‘energy balance’ and you stay the same weight. On the other hand, if you consume more calories than you use up, you’ll put on fat. This is called a ‘positive energy balance’.
 
If you want to be successful in your fat-loss campaign, don’t be in a rush. You should be looking at creating a slight negative energy balance, which is something you’ll be able to stick to long-term, rather than the ever-popular crash dieting strategies sold to us by the media. Crash dieting is unlikely to work long-term for various reasons. The motivation for rapid weight loss is short-term in nature anyway, because it centers on a ‘quick-fix’ philosophy. This invariably leads to the roller coaster of emotions that typifies the yoyo dieter. Determination to diet, rapid weight loss, weight-loss plateau, loss of willpower, return to old habits, rapid weight gain, guilt, new determination to diet, rapid weight loss… and so the cycle goes on. Most people put excess fat on slowly and progressively over time. This is called creeping obesity, so it’s totally unnatural (and very difficult) to lose fat quickly. All you’ll lose through crash dieting is a whole pile of muscle and water.
 
 
Starvation
This is an extreme example, yet it demonstrates the point rather well. If you don’t have any food coming in, your carbohydrate stores will run out quickly. Once this runs out, you’re left with fat and protein as fuel sources. In preference to using its fat stores, the body will metabolise protein for one logical reason. Protein constitutes the structure of our muscles and organs, all of which are living tissue, requiring energy to exist at rest. By whittling down these structures in return for energy, the resting metabolic rate of the body is reduced. With little or no calories entering the body, this is a survival mechanism that works pretty well, because energy is produced through a process that also reduces the metabolism, enabling you to survive for longer without food.
 
This is why starvation diets don’t work. Because when you stop eating, you lose loads of weight (muscle) and then when you get fed up (or think you’ve reached your goal weight), you start eating again. However, because your metabolism is suppressed, you initially store loads of fat, the muscle goes back on and ultimately you end up heavier than you were when you started.
 
 

The Best Way to Lose Fat for the Active Person

If you want to hold on to your muscle when you’re at negative energy balance, guess what? You need a diet rich in carbohydrate. Carbohydrate is said to have a protein-sparing effect, because in its absence, protein will be converted to carbohydrate through a process called ‘gluconeogenesis’. This enables your metabolism to run smoothly. In the absence of adequate dietary protein, your muscles get the chop! So, your first line of defence is to maintain a regular intake of carbohydrate to discourage protein metabolism. You’ll also want to ensure you get some quality protein sources too, so that any stray protein metabolism comes from your food and not your hard-earned muscle mass.
 
In order to create your negative energy balance and encourage fat loss, it goes without saying that you should be looking at keeping dietary fat intake as low as possible. This is after all, the stuff you’re trying to get rid of! At rest, most of your energy comes from fat. So if you’re not putting it into your body, you’ll be using the fat stored around your organs and under the skin to fuel your metabolism. Any calorie you put into your body that is excess to requirements will be stored as fat though, so losing it isn’t just about  following a low-fat diet, it’s about following a low-fat diet with a slightly negative energy balance.
 
 

Carbohydrate Gives You the Fuel to Train

So apart from sparing protein and preserving a high base metabolic rate, enabling you to burn more fat at rest, carbohydrate will provide you with the capacity to exercise effectively and at length. A diet of similar calorific value with a greater percentage of fat or protein will reduce your capacity to exercise. So it isn’t a logical choice if you’re a cyclist wishing to lose fat.
 
 

The Glycaemic Index - All Carbohydrates are Not Alike…

To further enhance the effectiveness of your fat-loss program, a little knowledge of the glycaemic index (GI) will help. The GI is a measure of how quickly the glucose from the food we eat gets into our bloodstream. It’s all measured against glucose, which is 100 and about the quickest, but there are one or two things quicker. Basically, the lower the GI, the longer the carbohydrate lasts, because it drip-feeds the metabolism and the less likely it is to be stored as fat. Big influxes of glucose from high GI foods force fat storage in the body’s attempt to reduce blood sugar. Low GI foods are more satisfying, are unlikely to leave you craving for more and are generally quite bulky due to their fibre content. This means that they usually contain less calories per serving.
 
Very active people should choose high GI foods immediately after exercise to aid carbohydrate storage, but if your aim is fat-loss, at all other times you’re better off going for low GI as often as possible. The mistake that many people make is that low GI foods are generally the starchy carbohydrates, but this isn’t necessarily the case. Fructose (fruit sugar) for instance has an extremely low GI, yet is intensely sweet. You can’t get more ‘starchy’ than a baked potato, yet these have a GI that’s right at the top of the scale. Do your research. There are plenty of books out there and information on the internet.
 

Don’t Forget to Exercise

It goes without saying that the more exercise you do, the more calories you’re going to burn, so whilst you’re sorting out what you’re eating, don’t forget to look at your weekly schedule and see if you can find a bit more time to get out on your bike. The most effective form of fat-loss exercise is prolonged steady low intensity exercise, because this burns more fat, but it requires time, a commodity many of us just don’t have. If you have all day, this is very effective. If you have limited time, you’re better off working harder for the time you do have.
 
If you can use the gym a couple of times during the week for instance, try to maximise your time there and don’t just stick to a steady pace in the belief that you’ll burn more fat. Ultimately, the more calories you can burn during a workout, the greater you’ll tip your energy balance to the negative. Higher intensity workouts during the week will boost your fitness too, giving you more power under the hood when you’re riding the bike at the weekend.
 
You should also look at incorporating some upper body weight exercises into your routine too. Weights of high repetition and light resistance will develop muscle density. Muscle is a living tissue, so the more of it you have, the greater your resting metabolism and the more fat you’ll burn at rest. Get the picture?

High Protein or High Carbs for Fat Loss?

Dieting is a massive industry and there’s a barrow-load of different opinions out there. But two that really contrast are the traditional high carbohydrate approach to fat loss, which I have outlined up to this point and the more recent high protein viewpoint endorsed by the famous Dr Atkins. There are of course diets that sit somewhere between the two like ‘The Zone’ and ‘Body for Life’. With celebrities attributing their new-found svelte physiques to a high protein diet, you’d be mad not to try it , wouldn’t you?
 

High Protein Nutrition for Fat Loss

Pro-protein protagonists put forward a very convincing case for following a diet low in carbohydrate, and high in protein. Here’s a summary of them:
 
Some research suggests that a high protein diet is better at maintaining a high resting metabolic rate than a high carbohydrate diet of the same calorie intake.
 
One piece of research has also demonstrated an 11% greater fat loss with a high protein compared to high carbohydrate diet.
 
High carbohydrate diets have been found to encourage insulin production following a meal, which has been linked to a greater potential to store fat.
 
High carbohydrate diets have been linked to increased release of serotonin, (a hormone that controls mood) and it is suggested that individuals over-eat carbohydrate rich foods in order to provide the brain with its seratonin fix. The argument is therefore that high protein foods increase feelings of satiety.
 
It’s theorised that psychologically, dieters consider that as a low-fat or ‘diet’ food contains less fat, they’ll eat more of it (low fat usually means high carbohydrate). One study showed that when given crisps with no nutritional information, the subjects of the experiment ate on average 61 calories worth. After being informed that the product was fat-free, energy intake rose to 111 calories.
 

These are some of the arguments against high protein for fat-loss.

Very low carbohydrate diets cause glycogen stores to be lost along with the water they hold. These diets also stimulate a process called ‘Ketosis’ where the body tries to form an alternative fuel source to carbohydrate. Ketones are highly toxic, so are excreted in the urine causing additional water loss. It is argued that this combined water loss causes weight loss, often misinterpreted as fat loss.
 
Ketosis causes bad breath, nausea and if you don’t drink enough water, it can kill you!
 
One piece of research comparing the ‘Zone’ diet with a high carbohydrate diet demonstrated that both produced equal amounts of weight loss. Yet the Zone diet raised harmful triglycerides in the blood to dangerously high levels.
 
High protein diets are typically very low in fibre. The scientific evidence clearly points to the incidence of colon cancer being lower in populations consuming diets high in fibre.
 
Many pro-carbohydrate people suggest that the high protein approach simply represents yet another low-calorie diet. The smaller the range of foods available, the lower the calories consumed. Removing carbohydrate from your diet also removes the temptation to add fat to food. Where are you going to put your butter or cream?
 
High protein diets stimulate calcium loss, reducing bone mineral density and increasing the risk of fractures/osteoporosis.
 
Low glycaemic index (GI) foods provide a gradual release of carbohydrate into the bloodstream encouraging only low to moderate insulin levels. Here the argument is that these foods are the most satiating, not protein.
 
 

Our Ancestors, Who is Right?

This is interesting:
 
“Take a look at the research by Professor Loren Cordain of Colorado State University.  You’ll see that our stone-age ancestors consumed moderate amounts of carbohydrate… Technologically simple cultures have similar eating habits and are free from many of the diseases that plague industrialised societies.” Christian Finn MBA: ‘Fit-Pro’ (June/July 2001).
 
“For the past 10,000 years our ancestors survived on a high carbohydrate and low fat diet. They ate their carbohydrate in the form of beans, vegetables and whole cereal grains. They ate their sugars in fibrous fruits and berries. Food preparation was a simple process; grinding food between stones and cooking it over the heat of an open fire.” Brand-Miller et al: ‘The Glucose Revolution’ (1999).
 

Making Sense of it All.

How physically active are you? Do you ride your bike every day, or just at weekends? Do you want to ride at a reasonable speed, or are you happy just pottering along? When push comes to shove, losing weight is all about creating a negative energy balance. This means that you need to have less calories coming into your body than you push out through metabolism and activity and there are plenty of ways of achieving this. You need to make a choice that is both healthy, workable and one that sustains enough bodily energy for you to get on with what you want to do in life.
 
If you exercise periodically and want to have a bit of zip in your legs, you should be able to get away with elevating your carbohydrate intake the day before you exercise. If you’re regularly physically active though, choosing a low-carbohydrate diet can only spell disaster. Your glycogen stores will be completely stripped of content and your capacity for exercise will be severely restricted.
 
“While the high-protein, high fat, low carbohydrate diet has reared its ugly head once again (it seems to return with a new name every 10 to 20 years), it is no better now than it was when it was first introduced. There is nothing in science or experience to suggest that this type of intake is useful for any athlete. For endurance athletes, all the literature makes it amply clear that the higher the carbohydrate intake, the better the performance.” Dr Dan Benardot: ‘Nutrition for Serious Athletes’ (2000).
 
 

What is Healthy?

In terms of health, again I can only offer my own point of view. Of course there are many other opinions out there.
 
I truly believe that a low fat, high carbohydrate diet is healthy, regardless of activity level as long as every effort is made to consume low-glycaemic index (GI) foods as the mainstay of your diet. These are typically unrefined whole grain cereals, pulses (beans and lentils etc), oats, pasta, brown or basmati rice and fruit/vegetables. I also firmly believe that the vegetarian regimen is very healthy one and that diets high in saturated fat are primarily responsible for the high levels of heart disease in the western world. I’m not adverse to the suggestion that refined high GI carbohydrates may also play a role though, but more so when combined with LACK OF EXERCISE.
 
I also feel that diets high in monounsaturated fat (with things like olive oil), typical of the Mediterranean region are healthy. The evidence for this is in the extremely low incidence of heart disease for these regions (the sun and lack of stress probably helps a tad), but I don’t consider this kind of diet the ideal springboard for fat-loss. Nor do I believe they’ll fuel you to do anything more than a trundle when it comes to riding your bike. With regard to the high protein diet, my major health concern would be the lack of dietary fibre, which could lead to various unhealthy complications.
 
I wouldn’t have spent so much time at the beginning of this article covering the importance of carbohydrate for physically active people if there wasn’t a mountain of validated research supporting it. It’s important to understand the debate before you make any decisions on the direction you want to take, but my overriding message is to keep it simple. If you stick to a negative energy balance and persevere, you will succeed.
 
Good Luck.
Matt Hart

“Published in Bicycling Australia magazine
www.bicyclingaustralia.com