Men require around 6% body fat for a healthy functioning body; anything more will slow you down in endurance racing. The top endurance athletes in the world can get close to this number for a short period around key races in the year, but 10% is a more realistic target for the weeks around goal race for the most dedicated top-level amateur athletes. Reaching minimal body fat percentages requires extreme discipline but reaching it while maintaining muscle mass is where the performance gains are realised.
The simplest way to ensure a faster 5k is to run light. Weight loss of even five pounds can improve your 5k time by anywhere from 5 seconds to a minute.Pete Magill
Healthy weight loss will increase your V02 max, reduce the impact on your muscles and joints, and improve your running economy. Combining these three improvements will make you faster, less prone to injury, and able to maintain high intensities for longer.
The process of losing weight, particularly if you lose it too quickly, will have a temporary negative effect on performance as you have lower muscle glycogen stores to fuel exercise. If you do not eat enough protein while cutting back on food, you might be losing muscles and fat, making you slower. Many people struggle to lose weight initially, even when they reduce their calories and increase exercise. It takes time for the body and specifically the metabolism to adjust.
To minimise the risk of the adverse effects:
- always eat some carbs within 30 minutes of a workout to restock glycogen
- target a maximum of 0.5kg weight loss per week
- perform strength training workouts two to three times per week
- use high-intensity interval training to increase your metabolism
- train daily to keep your metabolism going
If you are at the beginning of your endurance journey, then incrementally eating a healthier diet and gradually increasing your training volume is all you need to think about to move towards an optimum race weight. As your body adapts to regular training, becoming more efficient, and having your eating in a good place, you will have to become more thoughtful about reducing your excess fat.
Researchers at Oxford University suggest weighing yourself daily as feedback towards reducing body weight. The daily marker helps you self-regulate, letting you know if you are moving towards your goal weight or further away from it. With this information, you can constantly adjust your eating and training habits accordingly and then measure the effects of these changes, learning how your body reacts to different behaviours over time.
The effectiveness of self-monitoring is hypothesised to be based on a self-regulation process, whereby monitoring oneself allows for (1) the comparison of the current status to a previously set goal, thus providing (2) the opportunity to reflect on the effectiveness of previous behaviour, and enabling (3) the formulation of an action plan to reach the goal, which is followed by (4) the performance of the planned action (Boutelle, 2006; Kanfer & Karoly, 1972; LaRose et al., 2009)Kerstin Frie et al.
For most amateur runners, losing some body fat will make you run faster. Healthy weight loss for those without a medical condition is simple, eat better and move more. Try to keep weight loss to a maximum of half a kg per week. Keep your protein intake high and strength train to maintain muscle mass. To help you learn how your body responds to changes in your habits, weigh your self at the same time each day and reflect on how your behaviours affect your weight over time, then adjust these behaviours based on where you want your weight to be.
The longer the distance you race, the more critical being lean becomes. Focus on shorter races at first and let yourself get leaner over time as you increase your training volume and experience.