Diet vs. Exercise: What’s best for weight loss?

The debate as to whether nutrition or exercise is more important for weight loss is a big one, however, the answer is much simpler than you may think. Here is everything you need to know about diet vs. exercise for weight loss.

How does weight loss work?

For weight loss to occur, you must be in a calorie deficit. Weight loss occurs when your body is expending more calories than you are consuming and your body is forced to use stored energy for fuel.

Calories are the body’s form of energy. When you supply the body with more energy than required, in the form of calories from food and beverages, excess energy is stored as body fat. This fat tissue is a form of stored energy that can be used when the supply of energy, from food and beverages, is low.

Weight loss, also known as fat loss, occurs when the body is forced to use stored energy from body fat as fuel because the demand for calories exceeds the supply, which is known as a calorie deficit.

Diet is the only contributing factor to caloric intake, while exercise is one of multiple contributing factors to caloric expenditure, however, they both play pivotal roles in weight loss.

The Role of Diet in Weight Loss

Because a calorie deficit is essential for weight loss, diet plays a key role in weight loss. Not only is reducing how many calories you consume a fail-safe strategy for weight loss, but it is generally much easier to manage your caloric intake through diet than exercise.

For instance, cutting 200 calories from your diet may be as simple as cutting out a vanilla latte or a couple of tablespoons of peanut butter, whereas it could take 30 minutes of brisk walking or a 20-minute HITT workout to burn 200 calories (1, 2).

Here are some of the ways that diet helps with weight loss:

1. Manage Calorie Intake

Diet is the best way to manage calorie intake for weight loss. Because the calories we consume come directly from the food we eat and the beverages we drink, managing our diet is the best way to create a calorie deficit for weight loss. While there are many ways to restrict foods to restrict calories, research shows that any diet that limits your food intake to create a calorie deficit will enable weight loss, as long as you adhere to it (3).

2. Support Satiety Signals

While it is natural to feel some level of hunger in a calorie deficit, you consume less energy than required after all, the macronutrient composition of the calories you consume can have a big impact on your hunger and satiety signals in the process. Consuming adequate protein and fiber can help to stave off hunger and promote feelings of fullness in a calorie deficit. Research shows that a high-protein diet can naturally help individuals regulate their calorie intake, lose weight, and keep it off (4, 5, 6).

3. Preserve Muscle Mass

Consuming adequate protein can also help to preserve muscle mass during a weight loss phase. Unfortunately, if adequate protein is not consumed during a weight loss program, the body will convert stored protein into glucose for energy, and cause muscle loss to occur. Not only can this have negative effects on general health, but it can negatively impact metabolic rate, which can make weight loss more difficult in the long term. Evidence suggests that consuming 0.7 grams of protein per pound of body weight per day is an optimal starting point for weight loss goals (7).

4. Boost Metabolism

In addition to preserving muscle mass, consuming adequate protein can also increase your energy expenditure through the thermic effect of food (TEF). Also known as diet-induced thermogenesis, TEF is the energy expended to digest, metabolize, absorb, and store the food that you eat and, of the three macronutrients, protein has the highest TEF at 20-30% (8). Meaning, if you consume 200 calories of protein, 40 to 60 of those calories will be used to metabolize them.

5. Support Sustainability

Learning how to restrict calories while still enjoying the foods you love is vital for long-term weight loss success. Following a dietary pattern you enjoy, while consuming adequate protein and fiber, is one of the best ways to drop pounds and promote sustainable weight loss (9).

6. Support Overall Health

While a calorie is a calorie and a calorie deficit is required for weight loss, not all calories are equally as nutritious. By eating in a calorie deficit while prioritizing nutrient-dense whole foods, such as fruits, vegetables, whole grains, beans, lentils, nuts, seeds, meat, poultry, seafood, and dairy, you can help to ensure you are consuming adequate micronutrients to support your overall health while losing weight. While controlling calorie intake is integral for weight loss, it should not be done at the expense of general health, and being mindful of food choices is the best way to ensure we are consuming adequate vitamins and minerals while creating a calorie deficit at the same time.

The Role of Exercise in Weight Loss

When you exercise you burn calories and the more calories you burn the more energy you expend, however, exercise alone is a less-than-effective strategy for weight loss.

While physical activity has many health benefits, and should most definitely be included in a healthy lifestyle, it generally burns fewer calories than people think. Even the most effective workout will only burn several hundred calories, which can easily be consumed through food in a matter of minutes. For this reason, exercise is best paired with dietary changes for an effective weight-loss strategy.

Here are some of the ways that exercise helps with weight loss:

1. Increased Calorie Expenditure

Not only is daily physical activity beneficial for overall health, but exercise is a great way to increase energy expenditure to support the creation of a calorie deficit required for weight loss. While different exercise programs require different energy outputs, all forms form exercise increase total calories burned. Even low to moderate-intensity forms of activity, such as walking, yoga, or biking, can have a significant increase in your total daily energy expenditure (TDEE).

2. Build Muscle Mass

Specific forms of exercise, namely resistance training, are incredibly beneficial for weight loss as they help to maintain and build muscle mass. Muscle mass is one of the key components in basal metabolism rate (BMR) and individuals with increased muscle mass have been shown to have a higher resting metabolic rate (RMR) (10). Although cardio may burn more calories during exercise, resistance training is more likely to enhance fat loss than cardio, as resistance training will increase the energy you expend when you are not working out (11).

3. Maximize Metabolism

A good exercise program can increase energy expenditure while exercising, as well as increase energy expenditure at rest, which can maximize metabolism and expedite weight loss. By increasing general physical activity and building muscle, you can increase your exercise activity thermogenesis (EAT), non-exercise activity thermogenesis (EAT), AND basal metabolic rate (BMR) to increase your total daily energy expenditure (TDEE) and make the creation and maintenance of a calorie deficit much easier.

4. Enhance Appetite Regulation

While you might think exercising more might lead you to eat more, research suggests that a strategically programmed exercise program may enhance satiety signals by regulating hunger hormones (12, 13). This can help lead to better appetite regulation and increase the likelihood you will stick to your weight loss plan.

5. Increase Diet Flexibility

Increasing physical activity provides more leeway and diet flexibility when trying to lose weight. Exercising one, two, or a few times per week can help you expend anywhere from a couple hundred to a couple thousand more calories, which not only increases your energy expenditure but allows for more wiggle room for treats. Not only will this make losing weight easier, but it will make the entire process more enjoyable and sustainable.

Other Factors that Influence Weight Loss Success

In addition to diet and exercise, several other factors can influence the success of a weight loss program.

• Consistency – Diet and exercise are integral to weight loss, however, if not managed consistently, losing weight will be very difficult. While a weight loss plan does not need to be executed perfectly 100% of the time, consistency and adherence are key for success.
• Adaptation – The ability to adapt and be resourceful is a highly underrated factor in the success of a weight loss plan. When life throws you challenges, the more you can pivot and modify your plan to make things work the easier it will be for you to reach your weight loss goals.
• Lifestyle – While these will not impede weight loss if a calorie deficit is created, lifestyle factors such as stress and sleep can affect the body’s BMR and, in turn, energy expenditure which can make weight loss much more challenging.

Benefits of Combining Diet and Exercise for Weight Loss

Research has shown that weight loss programs based on physical activity alone are less effective than programs that combine diet and exercise in both the short and long term (14, 15).

So, is diet or exercise better for weight loss?

While both diet and exercise play vital roles in weight loss, diet is the best way to manage caloric intake to create the calorie deficit required for weight loss to occur. Understanding how many calories you need to consume to create a calorie deficit, whether you choose to count calories or macros or not, is one of the best ways to support a weight loss goal.

The Bottom Line

In the diet vs. exercise for weight loss debate, diet is most important. While diet and exercise play valuable roles in weight loss, diet has a greater impact as it helps to directly manage calorie intake to create a calorie deficit which is the sole requirement for fat loss. That said, both diet and exercise should be utilized in a weight loss program, as they will help to enhance satiety signals, maximize metabolism, maintain and build muscle mass, and increase sustainability.