Gradual loss of body fat can have a positive effect on running performance, but such drop-offs must be undertaken carefully, and are not without health risks. Combine a training plan with small but steady increases in volume and intensity with an eating program that eliminates a moderate number of unnecessary calories without harming overall nutritional to improve your body composition. The following excerpt about losing body fat safely is from Running Science by Owen Anderson.
How runners can lose body fat:
- Increase running volume or upgrading the intensity of training sessions
- Trim total food consumption
- Change the quality of the diet: replace high-calorie foods with less calorie-dense foods such as fruits, vegetables and grains
- Employ a combination of these strategies
More: Running to Lose Weight
Experienced runners with significant training volumes often find it impractical to lose weight by expanding training. A realistic, relatively safe rate of weight loss is believed to be about 1 pound per week, which would require an increase in energy expenditure through additional running or cross-training of about 500 calories a day. If eating habits remain the same, 4 to 5 miles of additional daily running would be required to induce this energy shortfall, or about 28 to 35 extra miles per week. Such an increase in training might represent a reasonable goal for low-volume runners, but it would be a near impossibility for busy runners who are already logging about 35 miles of running per week.
How to Improve Body Composition Through Diet
This means that a change in dietary intake will be the key factor in weight loss for many runners who train on a regular basis. Such runners have already come close to optimizing their rates of energy expenditure, and thus need to explore ways to reduce energy intake. Reducing the percentage of fat in the diet can be an effective way to enhance leanness. Compared with carbohydrates and protein, dietary fat has an increased potential for preserving weight or stimulating weight gain in runners for the following reasons:
- Each gram of fat in the diet has more than twice as many calories as a gram of carbohydrates or protein.
- Fat is digested and assimilated quite efficiently compared with carbohydrates and protein. Thus, little energy is expended to process fat. Almost all of fat's energy can be used for metabolic requirements, training, or for the storage of new fat within the body.
- Unlike carbohydrate intake, which leads to heightened carbohydrate metabolism, the ingestion of fat does not stimulate increased fat oxidation.