Diet or Exercise: Which One is More Important for Weight Loss?

by Marixie Ann Obsioma, MT, undergrad MD on November 20, 2019
Last updated on May 23, 2021

Whether you intend to slim down for a special event or simply improve your health, weight loss is a common goal. However, there are no shortcuts or prodigious formulas. Weight loss, in all circumstances, must be a progressive process. There must be a clear understanding of how weight loss occurs and the factors that may affect its rate.

things that you need for diet and exercise; sneakers, dumbells, apples, and a bottle of juice

To suppress a kilogram without putting risks on your health, you must obtain a balance between a suitable diet, which provides us nutrients, and an extra energetic expense that we get by practicing the most appropriate exercises. Read on to know more.

How Does Weight Loss Occur?

Weight loss occurs when you regularly eat fewer calories than you burn daily. On the other hand, weight gain happens when you consistently take more calories than you burn. Any food or drink you consume that has calories adds to your total calorie intake.

That said, the count of calories you burn daily, which is more popularly known as calorie or energy expenditure, is a little more complicated. It has 3 major components (1).

  • Resting Metabolic Rate (RMR): This is the count of calories your body requires to sustain normal bodily functions like breathing and circulation.
  • Thermic Effect of Food (TEF): This pertains to the calories needed for the digestion, absorption, and metabolization of food.
  • Thermic Effect of Activity (TEA): These are the calories you use during physical activity. TEA may also include non-exercise activity thermogenesis, which accounts for those you use for activities like fidgeting and yard work.

Burning the same amount of calories as you consume will only keep your current body weight. If you want to slim down, you must either take fewer calories or burn more through exercise.

What Are the Factors That May Affect Weight Loss?

While combining a healthy diet and good exercise habits are beneficial, there are still several factors that can affect the rate at which you lose weight.

1. Age

Alterations in body composition naturally occur with increasing age. As you age, more fats are being stored and muscle mass decreases. This change, together with other factors like the decreasing calorie requirements of your major organs, causes a drop in RMR (2, 3).

Adults age 70 and above can have RMRs that are 20-25% lower than younger adults (4, 5). Low RMR can make weight loss more difficult with age.

2. Gender

Fat to muscle ratio will greatly affect your ability to slim down. This ratio is often greater in women than men, hence they have a 5-10% lower RMR (5). This just means that women generally burn 5-10% fewer calories than men of the same height at rest. Thus, men will lose weight faster even after following a diet with the same amount of calories.

This was proven true by an 8-week study involving more than 2000 participants who were on an 800-calorie diet. Results showed that men lost 16% more weight than women (6). Their ability to maintain weight loss was not studied though.

3. Starting Point

Your current body weight may also affect the rate at which you lose weight. Expect the amount to be proportional to your initial weight, especially during the first few weeks. Heavier people will lose more pounds than those who are lighter. However, the rate of weight loss appears to be the same when it comes to the percentage (7).

For example, someone who weighs 300 pounds may lose 10 pounds after reducing their daily calorie intake by 500 for 2 weeks. Conversely, a person of the same gender and age weighing 150 pounds may lose just 5 pounds following the same method. Although the heavier person lost double the amount of weight, both of them lost an equal percentage of their body weight, which is 9.7%.

4. Calorie Deficit

As mentioned earlier, you must have a negative calorie balance to slim down. The extent of this deficit affects how fast you lose weight.

If you consume 500 fewer calories daily for 8 weeks, you are more likely to get greater weight loss than eating 200 fewer calories per day. However, do not make the calorie deficit extremely large because it is not sustainable. You might end up losing weight because of muscles and not fats. You’ll also risk yourself of nutrient deficiencies.

5. Sleep

Sleep is often overlooked, but it is a crucial component of weight loss. Lack of sleep can delay the rate at which you shed pounds. Studies show that even just one night of sleep deprivation can increase your cravings for high-calorie, low-nutrient foods (8, 9).

A 2-week randomized study revealed that sleeping for only 5.5 hours can cause you to lose 60% more body mass and 55% less body fat as compared to when you get more than 8 hours of sleep (10). Consequently, chronic sleep deprivation is associated with obesity, heart diseases, type 2 DM, and some types of cancer (11, 12, 13).

6. Medications

Several drugs, including anti-depressants and other antipsychotics, can hamper weight loss (14).

7. Medical Conditions

Illnesses, which includes depression and hypothyroidism, a condition that causes the thyroid gland to produce very few metabolism-regulating hormones, can delay weight loss and promote weight gain (7, 15).

8. Genetics and Family History

There is an established genetic component associated with overweight or obese patients, and it can affect weight loss (16, 17).

9. Yo-yo Dieting

Repeated loss and gain of weight can make weight loss more difficult with every attempt because of a low RMR (18).

How Can Eating Healthy and Exercise Help You Lose Weight?

Eating right and exercising on a regular basis can help you avoid excess weight.

Studies show that inactivity is one of the major factors in weight gain and obesity (19, 20). Being physically active is important to reach your weight loss goals. Regular exercise can help increase your metabolic rate to burn more calories (19, 20, 21, 22). More studies have shown that putting together aerobic exercise and resistance training can boost fat loss and maintain muscle mass, which are both important to keep excess weight off (20, 22, 23, 24, 25).

Aim for at least 150 minutes of moderate exercise weekly. If you cannot commit to this amount of time to exercise, find ways to increase your other physical activities throughout the day. Walk instead of driving, take the stairs instead of the elevator, and more.

Consuming a healthy and balanced diet can also help control weight. Real, good foods are packed with protein, which can boost your metabolism, reduce hunger, and affects hormones that help regulate weight (26, 27, 28). Fruits and vegetables contain natural sugars, not refined sugars. The latter is lined with obesity by increasing the production of the hunger hormone ghrelin and dimming your brain’s ability to make you feel full (29, 30, 31). Real foods are also rich in fiber, which help decrease the production of hunger hormones and increase those that keep you feeling full (32, 33, 34, 35). Evidence also shows that eating processed foods will not give you enough iron, which moves oxygen around your body. This will greatly limit your ability to burn calories during exercise (36).

Starting your day with a healthy breakfast can help avoid excessive hunger later, which could send you running to the nearest fast-food chain for lunch. Also, skipping breakfast can increase your blood sugar, which may promote fat storage. Include at least 5 servings of fruits and vegetables into your diet daily. These foods, which are nutritious and are low in calories, help with weight control. Control your refined sugar consumption. Choose lean meats for protein.

Both diet and exercise are equally important. Working out won’t help you lose weight if your diet is out of whack. You can keep running miles, but chances are high that results will be displeasing unless you change what and how much you are eating.

Other Health Benefits of Eating Healthy and Exercising

Aside from weight loss, eating healthy and exercising can offer a slew of benefits:

1. Disease Prevention

Making real food and exercise a part of your lifestyle may help reduce your risk of chronic diseases.

Eating patterns, which are based on whole, unprocessed foods, are known to reduce your risk of heart disease, DM, and metabolic syndrome (37, 38). Several observational studies also link the heavy consumption of fruits and vegetables to a decreased risk of some types of cancer (39).

Lack of exercise is also known to be a primary cause of chronic diseases (40). Regular exercise can improve insulin sensitivity, cardiovascular health, and body composition. It decreases blood pressure and fat levels too (41, 42, 43, 44). In contrast, a lack of regular workout can increase your belly fat and risks of chronic diseases and even death (41).

2. Increased Energy Levels

If you are always feeling tired and low in energy, you might want to check your eating habits and exercise routines.

As mentioned above, good eating patterns can help lower your risk of developing chronic diseases, which may also affect your energy levels and the way you feel on a daily basis. Choosing whole, nutritious foods will give your body the fuel and nutrients it needs to function properly (45). Also, irregular eating patterns, which includes skipping of meals, may cause fatigue (46). Extreme dietary restrictions will also result in low levels of calories and essential nutrients like iron, which negatively affects your energy level (47).

Exercise can be a real energy booster too! Evidence shows that 6 weeks of regular exercise can greatly help reduce feelings of fatigue (48). It has also been effective in increasing the energy levels of patients suffering from chronic fatigue syndrome (CFS) and other serious health conditions (49, 50).

3. Good Sleep

The quality and type of your late-night eating can impact both sleep quality and quantity. Evidence shows that a high-carb meal taken 4 hours before bedtime can help you fall asleep faster (51). A low-carb diet can also improve sleep (52).

Regular exercise can also help you relax and sleep better (53, 54). Evidence shows that 150 minutes of moderate to vigorous exercise weekly can offer as much as 65% improvement in sleep quality (55). Another study proved that 16 weeks of exercise can help insomnia patients sleep longer and more deeply (56). Elderly patients with sleep disorders benefited from regular exercise too (56, 57, 58)!

4. Better Memory

Not eating healthy and consuming excessive amounts of refined sugars can be damaging to your memory. These foods have a high glycemic index, thus digested by the body quickly and causing a spike in blood glucose level (59). Other studies have associated refined and processed sugars with dementia, reduced cognitive function, and poorer short-term and working memory (60, 61).

Exercise can help improve your brain function by increasing your heart rate and the flow of blood and oxygen to your brain. It stimulates the production of hormones that grow brain cells. Regular exercise has been shown to increase the size of the hippocampus, a part of your brain that is important for learning and memory (62, 63, 64).

5. Longevity

Consuming a wide variety of healthy, plant foods like fruits, vegetables, whole grains, seeds, nuts, and beans may help prevent diseases and promote longevity. Studies show that a plant-rich diet, which contains high amounts of nutrients and antioxidants, can lower one’s risk of heart diseases, metabolic syndrome, cancer, depression, brain deterioration, and premature death (65, 66, 67).

Staying physically active can also keep you healthy (68). As little as 15 minutes of exercise daily can help decrease your risk of premature death by 4% and add 3 years to your life (69). New evidence shows that people who exercised even for less than 150 minutes have lowered risk of early death by 22% (70).

Take-Home Message

While many factors affect your weight loss rate, putting both diet and exercise together can greatly help. Many people will try fad diets to bring quick results, but this is not healthy. It is the combination of the two that will propel you forward to natural weight loss and overall better health.


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