The Role of Exercise in Health and Weight Loss -

Kaitlin Little

In 2018, the Department of Health and Human Services released new Physical Activity Guidelines for Americans with one key message: “move more and sit less.” This overarching recommendation comes from new research that shows physical inactivity is now the fourth leading risk factor for mortality worldwide.

Physical inactivity may be responsible for up to 30% of heart disease, 27% of diabetes, and 25% of breast and colon cancer globally. Despite these serious health implications, only a third of Americans currently reach the nationally recommended level of physical activity each week. [1]

Physical Activity Guidelines for Americans

For adults to stay healthy, the new guidelines recommend at least 150 to 300 minutes of moderate-intensity, or 75 to 150 minutes of vigorous-intensity aerobic exercise per week, along with at least two days of full body muscle strengthening exercises. Adults seeking additional health benefits should aim for more than 300 minutes of moderate-intensity exercise each week.

Moderate-intensity aerobic exercise is strenuous enough to burn off three to six times as much energy as you would normally burn during rest (also known as 3 to 6 METs). Metabolic equivalents, or METs, are often used to measure the intensity of exercise relative to rest. Examples of moderate-intensity aerobic exercise include brisk walking, light cycling, or doubles tennis. Heavy household chores that accelerate your heart rate noticeably like mowing the lawn, cleaning the windows, or vacuuming are also considered moderate-intensity activities.

Vigorous-intensity aerobic exercise burns more than 6 METs and requires large amounts of effort that substantially increases your heart rate. Examples of vigorous-intensity exercise include running, walking uphill, fast swimming, fast cycling, and competitive sports.

But, the guidelines make it clear that any amount of movement is better than none. In fact, Americans can gain health benefits from small increments of exercise of just a few minutes throughout the day.

Immediate Health Benefits of Exercise

Most of us know it’s healthier to be physically active. But sometimes reminding ourselves about the benefits can spark the motivation needed to get the wheels in motion. Fortunately, you don’t need to wait long to reap the rewards of physical activity such as:

A Better Nights Sleep

Physical activity is directly correlated with several sleep outcomes. Even slight increases in exercise can have an immediate, positive impact on sleep quality as well as sleep onset and sleep efficiency, which means that you can fall asleep faster, remain in a deep sleep for longer, and experience less daytime sleepiness.

Exercise can also improve sleep quality for individuals with insomnia, anxiety, and depression, as well as reduce reliance on medications used to aid sleep. [2] [3]

But the timing of exercise is crucial. According to a recent systematic review of 23 clinical trials, vigorous exercise performed less than one hour before bedtime can negatively impact total sleep duration, sleep efficiency, and your ability to fall asleep. [4] Morning workouts may be ideal, but if you’re not an early riser, aim to squeeze in a workout during your lunch break or after work.

Improved Brain Function

Exercise may make you smarter! Over the last decade, neuroscientists have accumulated a large body of evidence that clearly demonstrates the acute benefits of physical activity on cognitive processing.

These studies compared brain performance immediately before and after aerobic exercise. The results consistently showed that exercise can temporarily improve memory, attention and reaction times, along with the ability to plan, organize, and control emotions. These acute effects on cognitive processing can last for up to 30-60 minutes post-exercise. [5]

Enhanced Mood

Ever heard your gym buddies rave about their post-workout high? According to science, they might actually be on to something. Strong research shows that exercise improves mood and decreases feelings of depression, anxiety, and stress. [6]

Two key physiological mechanisms can help explain these positive effects. First, exercise triggers the release of endorphins, which are chemical messengers that act like “natural morphine” to enhance mood and reduce stress. Second, exercise increases synaptic transmission via chemical messengers such as serotonin and dopamine, in a way similar to antidepressant drugs.

Several different psychological theories also shed light on why exercise can enhance mood. Exercise provides opportunities for social interaction, enhances self-confidence through success, and provides a physical challenge that can serve as a distraction.

Long-term Health Benefits of Exercise

Everyone, regardless of their age, can reap long-term health benefits from regular exercise which include the following:

Reduced Risk of All-Cause Mortality

Over 100 epidemiological studies have investigated the relationship between physical activity and risk of death from all causes. Based on these studies, it has been estimated that people who are physically active for at least 150 minutes a week have a 30% lower risk of all-cause mortality compared to inactive individuals. [7]

Importantly, health benefits such as improved cholesterol, lower blood pressure, and reduced inflammation start to accumulate with even small improvements in physical fitness.

Increased Life Expectancy

Physically active people, regardless of their weight, can expect to live a longer life. Even increasing physical activity levels to just 75 minutes of brisk walking per week can add an additional two years to your life.

These findings are supported by data pooled from six prospective cohort studies in the National Cancer Institute Cohort Consortium, involving nearly 700,000 individuals, that found higher levels of exercise are associated with increased life expectancy. [8]

Enhanced Cardiorespiratory Health

Cardiovascular disease has been the leading cause of death in the United States for decades. Cardiovascular disease refers to conditions that affect the heart and blood vessels, such as heart attack, stroke, and heart failure.

The good news is you can vastly improve the health of your heart, lungs, and blood vessels with regular aerobic exercise such as walking, cycling, swimming, or skipping. A recent systematic review of 30 clinical studies revealed that physical activity significantly reduces the risk of developing cardiovascular disease. [9]

Furthermore, regular low-intensity aerobic exercise is beneficial for patients with established cardiovascular disease. For example, one systematic review of 48 clinical trials found that patients who participated in a cardiac rehabilitation program significantly reduced their risk of premature death from any cause. [10]

Stronger Bones, Muscles, and Joints

Once we reach adulthood, we can no longer increase our bone mineral density. Therefore, building strong, healthy bones through adequate nutrition and weight-bearing exercise is essential during childhood and adolescence, after which preservation becomes key. Fortunately, physical activity during adulthood can slow this age-related decline in bone mineral density.

Regular weight-bearing exercise, such as treadmill walking, in combination with progressive resistance training, appears to have the greatest protective effect on bone mineral density. For example, a clinical trial found that combined resistance training and weight-bearing exercises were more effective at preserving hip and lumbar spine bone mineral density in post-menopausal women compared to resistance training alone. [11]

If you already have a chronic musculoskeletal condition, such as osteoarthritis or rheumatoid arthritis, regular exercise can help to improve range of motion, maintain function, and reduce pain. [12]

As we age, muscle mass and muscle strength also decline due to hormonal changes. Engaging in regular resistance training, and to a lesser extent, aerobic exercise, throughout the lifespan helps to preserve muscle mass, strength, and power. Progressively increasing the frequency and intensity by lifting heavier weights or increasing your repetitions results in greater improvements, regardless of your age.

Improved Physical Functioning & Reduced Falls

One of the greatest benefits of remaining physically active throughout your life is that exercise increases your functional capacity, allowing you to maintain your independence for longer. Functional capacity refers to the ability to perform everyday tasks, such as carrying groceries, climbing stairs, taking a shower, or playing with grandchildren. Loss of functional capacity is more common among inactive adults. But increasing your physical activity levels can help delay and prevent functional decline at almost any age.

Maintaining physical activity levels later in life can also reduce the risk of falls and fall related injuries by improving and preventing the loss of strength, balance, and coordination. Fall related injuries, such as hip fractures are very common among older adults and can have a very negative impact on overall health and quality of life.

Improved Brain Health

Maintaining a physically active lifestyle has beneficial long-term effects on the brain. Emerging research has suggested that exercise may facilitate neuroplasticity, the process of forming new connections within the brain. [13]

In youth, physical activity can improve brain development and future academic achievement. A recent systematic review reported that 98.5% of the studies found a positive association between school-based physical education and academic performance. [14]

Research also shows that regular exercise can improve dementia and cognitive impairment in older adults. A study involving almost 6,000 U.S women over the course of eight years found that those with higher physical activity levels were less likely to have cognitive decline. [15] Consistent with these findings are structural imaging studies that show physically active individuals have more brain grey matter than sedentary people. [16]

Exercise in Weight Management and Weight Loss

Exercise plays an important role in creating an energy deficit necessary for weight loss and weight management.

Does Exercise Help With Weight Management?

Strong evidence shows that regular exercise helps people maintain a stable weight over time. For example, in a 30-year study, females who exercised at least 150 mins/week gained just 8 lbs compared to less active women who gained an average of 21 lbs. [17]

If you have recently lost weight, exercise can play a pivotal role in preventing weight regain too. One excellent study involving 32 previously obese woman found that exercise in the range of 900 calories/day (the equivalent of 80 minutes/day of moderate activity or 35 minutes/day of vigorous activity) was key to achieving energy balance and maintaining weight loss. [18]

Does Exercise Help Weight Loss?

Combining exercise with a healthy diet is the most effective way to lose weight, rather than depending on calorie restriction or exercise alone. In fact, a systematic review of studies with a minimum of 1-year follow-up found that individuals who used exercise alone for weight loss experienced minimal results, while those who used exercise and diet achieved moderate results. [19]

If you are beginning a weight loss journey, the good news is that regular physical activity provides all the major health benefits mentioned above, no matter how your weight fluctuates over time.

How Much Exercise is Needed for Weight Loss?

Everyone loses weight at a different rate depending on a range of individual factors. Therefore, you may need to do more than the equivalent of 150 minutes of moderate-intensity exercise each week to lose weight.

Researchers at Queen’s University in Ontario demonstrated a weight loss of 17 lbs in 16 obese men in an exercise-only group for 3 months. These men lost a greater percentage of fat mass, in particular, abdominal and visceral fat, compared to men assigned to a diet-only group. However, the exercise prescribed was the equivalent of 60 min/day, which is significantly more than the minimum national guideline of 150 min/week. [20]

According to the American College of Sports Medicine (ACSM), those who want to lose a substantial amount of weight (more than 5% of body weight) or prevent weight gain after weight loss should aim for 250 minutes of moderate-intensity activity per week. For individuals aiming to maintain their weight, 150 to 250 minutes of moderate intensity activity per week is recommended. [21]

How Does Exercise Help Weight Loss?

Engaging in any type of exercise will increase your daily energy expenditure and contribute to an energy deficit necessary for weight loss. Aerobic exercise of moderate-to-vigorous intensity can also increase basal metabolic rate. Your basal metabolic rate (BMR) refers to the number of calories your body expends at rest on cellular processes, such as repair and maintenance. As a result, increasing your BMR means your body burns more calories at rest, leading to a larger energy deficit.

Furthermore, all types of exercise, especially muscle strengthening exercises can help preserve lean muscle mass. A higher percentage of lean muscle mass further increases resting metabolic rate, as each pound of muscle burns roughly six per day calories at rest.

There is No Substitute for Exercise

Regular exercise is an essential part of a healthy lifestyle and one of the best ways you can improve your health at any age. Engaging in regular exercise makes you feel better, sleep better, function better and reduces your risk of most chronic diseases. That said, anyone who has a chronic health condition, or has been inactive for an extended period of time, should consult with their health care provider before embarking on an exercise program.

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