If you regularly go running 3 miles a day, you've developed a fantastic habit for reaching your weight loss goals. The key to losing weight is establishing a caloric deficit, or burning more calories than you take in, and running is great for burning calories. But, depending on your eating habits, you might need to make those runs a little longer, or make a few healthy, sustainable tweaks to your diet to see the fat really come off.
If you're running 3 miles a day and sticking to a nutrient-rich diet, odds are good that you're exercising enough to burn excess body fat.
Running the Calories Away
The basic rule of weight loss is that you have to establish a calorie deficit or, to put it another way, you must burn more calories than you take in. Although every little bit of physical activity you do counts toward that deficit, running is particularly effective because it burns a lot of calories quickly.
The exact number of calories you burn during a workout depends on many factors, including your weight, body composition and how hard you work out. But numbers from Harvard Health Publishing offer a good place to start calculating just how quickly the weight might come off. For example, if you weigh 125 pounds and run 3 miles at 5 mph (or a 12-minute mile), you'll burn about 288 calories on your run. If you weigh 185 pounds and run at the same speed, you'll burn about 426 calories.
In the absence of medical conditions, genetic variations or prescription medications that complicate your weight loss, losing a pound of body fat requires you to burn about 3,500 calories more than you take in. Given those calorie-burn estimates, it would take the 125-pound runner a little less than two weeks to lose a pound of body fat, while the 185-pound runner would lose almost a pound a week.
Those weight-loss estimates may not sound as dramatic as the promises made by fad diet creators or on late night infomercials, but they are sustainable. Unlike fad diets and other extreme weight-loss programs, making regular exercise a part of your daily life will help you not only lose the weight but also keep it off over the long term.
Read more: 17 Reasons to Start Running
Some Help From the Kitchen
If you're running diligently but not seeing weight loss, your problem might be in the kitchen. Remember, to lose weight you need to burn more calories than you take in — so poor eating choices can cause you to take in so many calories that you negate all the effort of that running.
If you're ready to get as serious about your diet as you are about your running, there are a few things you can do. Start by focusing on healthy diet choices:
- Eat a variety of colorful vegetables and fruits.
- Choose low-fat dairy foods.
- Opt for high-quality protein sources such as fish, nuts and lean meats.
- Limit your intake of saturated and trans fats, sodium and added sugar.
- Consume alcohol in moderation, if at all.
If you keep running, it might be all you need to do to get your weight heading in the right direction. However, if you feel your diet needs even more attention, you can keep a food diary to track your calorie intake. Ideally, for weight maintenance, it should fall near the estimated daily calorie intakes given by the U.S. Department of Health and Human Services. These vary by gender, age and activity level. For example, an active 35-year-old man should eat around 3,000 calories per day, while an active 45-year-old man only needs about 2,800 calories. An active 45-year-old woman should eat around 2,200 calories per day. To establish your calorie deficit, either slightly decrease your calorie intake or increase your level of physical activity.
What Else Is Going On?
So you're running 3 miles a day and diligently tracking your calorie intake, yet the weight still won't come off. What on earth is happening? It's possible that some of your other lifestyle habits are causing problems. Of particular note, irregular or insufficient sleep — and maybe even too much sleep — can leave you at increased risk for obesity.
Understanding of the relationship between sleep and obesity — itself a complex, multifaceted condition — continues to evolve, but this much is clear: In a study of almost 120,000 people, published in an April 2017 issue of the American Journal of Clinical Nutrition, researchers found that getting less than seven hours of sleep or more than nine hours of sleep exacerbated genetic predispositions to obesity.
"Catching up" on sleep over the weekend doesn't necessarily help, either. According to a study published in a March 2019 issue of Current Biology, sleeping longer on the weekends to make up for sleep deprivation during the week did not prevent the subjects from gaining weight and developing decreased insulin sensitivity.
There's also a clear relationship between stress and obesity. Again, scientists' understanding of the mechanism continues to evolve, but as published in April 2018 in Current Obesity Reports, not only do long-term cortisol levels strongly correlate with obesity, but it's also possible that variations in glucocorticoid action — essentially, a feedback mechanism for your immune system — also affects your likelihood of developing obesity in response to stressors.
Another factor you should consider is hydration. Although the mechanism isn't clearly understood yet, a data review published in a June 2016 issue of Frontiers in Nutrition notes that in animal studies, increased hydration led to increased weight loss and that human studies offer data that is consistent with the same hypothesis. So if you're not getting enough sleep or enough water, your body might be showing the effects of that deprivation.
Am I Overdoing It?
If you're already used to running 3 miles a day and your body continues to feel good, keep up the great work! But, most people find that they need at least one day of rest or gentle "active recovery" workouts like walking to balance out their more intense workouts — and if you're just starting out, you might need more frequent rest.
Let your body be the guide to whether you're working too hard. Although you might feel tired at the end of your run, the overall net effect of regular exercise should be more energy in your everyday life. If you find yourself experiencing classic symptoms of overtraining, such as excessive fatigue, your normal runs feeling harder, disturbed sleep, feeling edgy or agitated, losing your appetite or struggling with nagging injuries, it's a sign that you need to dial back your workouts.
If the overtraining symptoms don't recede as you dial things back, it's time to speak with a medical professional to find out if something else might be behind your symptoms.
Read more: 17 Proven Motivations to Get You Running
Running 3 miles a day is a high-impact exercise, which not every body tolerates well — especially on an everyday basis. Wearing cushioned running shoes and running on soft surfaces, such as wood chips, dirt or grass, can help; but if your joints just don't love running as much as you do, consider taking at least some of your workouts to an elliptical trainer or even water jogging in a swimming pool, using a flotation belt to keep you afloat as you "run" against the resistance of the water.
- American Council on Exercise: "9 Signs of Overtraining"
- Harvard Health Publishing: "Calories Burned in 30 Minutes for People of Three Different Weights"
- Health.gov: "Dietary Guidelines for Americans, 2015-2020: Chapter 1. Key Elements of Healthy Eating Patterns"
- Health.gov: "Dietary Guidelines for Americans, 2015-2020: Appendix 2. Estimated Calorie Needs Per Day, by Age, Sex, and Physical Activity Level"
- Current Biology: "Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation during a Repeating Pattern of Insufficient Sleep and Weekend Recovery Sleep"
- Frontiers in Nutrition: "Increased Hydration Can Be Associated With Weight Loss"
- The American Journal of Clinical Nutrition: "Sleep Characteristics Modify the Association of Genetic Predisposition With Obesity and Anthropometric Measurements in 119,679 UK Biobank Participants"
- Current Obesity Reports: "Stress and Obesity: Are There More Susceptible Individuals?"