The National Weight Control Registry is an 8 year old project that has studied weight loss in 3500 extremely obese patients who lost (and maintained the loss) of an average of 60+ pounds. The common factor?? A high level of physical activity with an average weekly expenditure of 2545 exercise Calories in women and 3293 Calories in men (equal to an hour of moderate physical activity per day) coupled with an estimated intake of 1500 Calories per day. These Calories were eaten in 4 or 5 small meals throughout the day rather than skimping on breakfast and lunch and then eating a much larger meal at night. And it was a low fat diet with 23% of total Calories coming from fat. Most had failed to maintain their weight loss with other weight loss regimens, and almost universally attributed the success in this program to the sustained increase in their weekly level of physical activity.
Physical activity has a positive effect on your weight and figure by:
WEIGHT LOSS(IN LBS) = (CALORIES BURNED - CALORIES CONSUMED)/3500
Cycling will increase your daily Caloric output in two ways. First, and most obvious, is the energy required to move you and your bicycle against the resistance of air and gravity. A second, more indirect effect is through subtle changes in your daily routine to include more physical activity (such as walking up a flight of stairs instead of taking the elevator) because of an increased sense of vigor and well-being.
Many dieters worry that increased physical activity will increase their appetite. However a recent carefully controlled study of overweight individuals did not reveal a proportionate increase in appetite with exercise, lending support to the positive role of physical activity in reaching the goal of a negative Caloric balance and resulting weight loss. In fact, vigorous exercise actually suppressed appetite for several hours, suggesting that this short term effect can be used as an effective appetite control strategy by planning your exercise immediately prior to your major meal of the day.
Regular exercise also increases your basal metabolism rate or BMR (the number of Calories utilized by the body at rest to maintain basic life processes). An increased BMR is associated with all aerobic conditioning activity and is maintained with as little as 30 to 40 minutes of exercise 3 to 4 times a week. One study indicated that the increase in BMR with regular exercise may be even more pronounced in the older athlete.
Not only is there an increase in your overall BMR with regular exercise, there is an additional 12 hour post-exercise boost in the BMR. As a rule of thumb, this adds 15 bonus Calories for every 100 Calories burned during your aerobic activity. To capitalize on this post exercise bonus, consider two (or more) rides per day - perhaps in the morning and after work - rather than a single ride of equal duration.
Finally, regular physical exercise will protect muscle mass (at the expense of fat) during periods of weight loss. In two groups (one active and one more sedentary) with an equally negative Caloric balance and an equal weight loss, the exercise group will lose less muscle mass than the diet only group.
A common question is whether exercise can facilitate selective fat loss from the limb(s) exercised i.e. can fat be taken off the thighs by bicycling. Unfortunately this doesn't happen. Take the extreme example of a regular or professional tennis player who uses one arm almost exclusively. Comparison of fat fold thickness in both arms will NOT demonstrate a difference or asymmetry between them. Thus any exercise will promote fat loss from the body as a whole but cannot be targeted to any specific body area. However, there is still the benefit of improving the tone of the muscle or muscle groups exercised which has the same apparent affect to "slim" the area.
Even if the duration of the faster ride were shortened so that total Calories expended were equal (but proportionally more fat Calories with the slower pace) during both rides, a recent study at Georgia State University demonstrated an equivalent weight change i.e. there was no support for the idea that metabolizing fat for energy resulted in a greater weight loss. Another study at West Virginia U. study assigned 15 women to a low intensity (132 beats per minute) or high intensity (163 bpm) exercise group, both exercising for 45 minutes, 4 times a week. There was a decrease in overall body fat the high intensity group, but not the low intensity one, further evidence that it is total Calories expended, not the source of those Calories (CHO vs. fat) that makes the difference in an exercise supported weight loss program.
It is the final balance between total Calories burned (from ANY source - carbohydrates, fats, or protein) and those eaten (i.e. the NET NEGATIVE CALORIC BALANCE) that determines whether weight is gained or lost. The advantage of riding more slowly is that it may make the ride a more enjoyable experience for the novice rider, and the pace can be maintained for hours. If you have only a limited amount of time to ride, the faster your average speed, the more Calories you will burn and the more weight you will shed.
In fact there has been speculation that when you exercise at a slow pace, and preferentially burn fat Calories while maintaining muscle glycogen stores, any post ride carbohydrate loading may find the "tank full" (i.e. muscle glycogen stores) so to speak, and any additional carbohydrate Calories will be converted into fat instead. The bottom line is to ride at a pace that is comfortable for you, push yourself occasionally for the cardiovascular benefits, and avoid eating more Calories than you expend if your goal is to lose weight.
Another suggestion has been that caffeine (3 to 4 cups of coffee) per day, because of it's enhancement of fatty acid metabolism, would facilitate weight loss. There is no evidence to support this approach, perhaps related to the fact that the regular use of caffeine eliminates this particular physiologic effect.
The Zone by Barry Sears takes a unique approach to weight loss. He claims that his relatively high fat diet (40% carbohydrates, 30% protein, 30% fat vs the usual athlete's diet of 60/15/25) not only provides increased athletic performance but also promotes weight loss. Although this idea has been questioned and performance experts are appropriately skeptical as to the benefits of fat in supporting aerobic exertion, recent evidence has suggested that a diet can be too low in fat and groups on higher fat (percentage wise) diets do effectively lose more weight. (When used in a diet, a 33% fat diet was more effective in achieving weight loss than a 20% diet. Int J Obesity 2001:25:1503-1511.)
According to his theory, too much carbohydrate intake causes obesity as well by stimulating the pancreas to release excessive amounts of insulin. He then speculates that over time the body becomes resistant to insulin causing the pancreas to secrete even larger quantities. And these high levels stimulate fat synthesis. The question remains as to whether this is a case of putting the cart before the horse with obesity, not high carbohydrate intake, leading to insulin resistance at the cell level with a secondary overproduction by the pancreas. And insulin sensitivity can be restored by weight loss.
To keep the controversy alive (see the study quoted two paragraphs above), a recent Cornell University study of volunteers on an ad lib (eat as much as you want) diet of either high (37%) fat or low (22%) fat content for 11 weeks demonstrated that those on a low fat diet ate fewer Calories and lost an average of 5.5 pounds - twice the loss of those subjects on the higher fat diet.
Another study in a British medical journal showed that obese subjects who lost weight maintained their weight loss better on a high carb diet. Again, it appeared that it was easier to eat excess Calories with a high fat than a high carbohydrate diet. And fewer Calories means less weight gain.
FIVE PRACTICAL TIPS
MY RECOMMENDATION
I think the following recommendation (from a conference presentation by Dr.
William Gavin, MD) pulls it all together for me.
"Patients who are overweight have an excess carbohydrate intake for their particular body habitus. The key for these people to lose weight is to reduce their carbohydrate intake in the short term. I believe the Zone diet works best if modified to include carbohydrate restriction at night. It is important to remember that although Calories may be taken in the form of carbohydrate, they will not be stored as carbohydrate in the body. The body stores only a limited amount of glycogen in the liver and muscles. After a body has filled those stores, excess Calories, even from carbohydrate, are stored as fat. My own particular regimen would involve the following points:
READER'S QUESTIONS
Q.I have been on the South Beach diet (low carbohydrates) and just cannot ride like I
have in the past. Suggestions? - JC
A.If you are in a state of Calorie deficit (which you need to lose weight), and also are eating minimal carbohydrates to supply those Calories, you have very little muscle glycogen - which means you can exercise at approximately 50% VO2max at best. And of course, you don't want to add back in excess daily carbohydrates or you lose the weight loss benefits. My recommendation is to calculate (approximately) the number of Calories you will use on the upcoming ride, and then eat the appropriate amount of carbohydrates to supply them either 2 hours before the ride, or split them between the 2 hour preride meal and the snacks on the bike. If you eat what you will burn, you should have the energy to exercise but none of the excess Calories to store as fat later on.
Q.I am totally confused! I go on a bike ride each day to lose weight and burn
200 Calories, but then I also have an energy drink to reload glycogen into muscles
which is 200 Calories. Therefore I have lost no weight? So how can I cycle to lose
weight if I should be reloading my muscles afterwards? - AW
A.You are correct - if you replace the Calories you burn, you will not lose weight. You replete muscle glycogen (only completely depleted after you have riden the equivalent of 2000 Calories) when you plan on riding at >50% VO2max the next day (that is the break point where you begin to transition to burning glycogen instead of just fat for energy). If you want to lose weight you need to burn more Calories than you ingest. Only replete completely if you are going into a competitive event OR don't care about losing weight.
Q.I have about 40 pounds to lose. I was doing no exercise and was eating a
diet (Weight Watchers guidelines) that was allowing me to merely maintain my weight. So
I got the bright idea to dust off my bike and start riding to work 3 days a week.
This is about 10 miles and has some really good hills. It ends up taking me about an
hour to do the 10 mile ride. I have been doing this for 8 weeks now and have not lost
one single pound! I've been eating the same diet, so what's up? I really want to
keep riding because I can tell I'm becoming more fit: I have more energy and I
don't have to stop on the big hills anymore. I'm sure it's good for my heart
and hopefully decreasing my risk of other diseases - S.
A. 10 miles is around 300 Calories, when ridden at your speed (covered over an hour). My guess is that the 900 Calories per week are being subtlely covered by your diet - unless you are extremely meticulous about weighing your portions. So I think you have two choices - and maybe a combination. First, you can increase your mileage - each mile is 30 Calories. And the other is to be even more focused on your portion sizes. Although it has never been proven, I also think that if you get your heart rate up to 80% max for 30 minutes 3 or 4 times a week, your metabolism remains reved up even when you get off the bike. So as a final thought, you could try to increase your speed (to get your heart rate to 80% max for your age group).