You may be familiar with sayings such as ‘You can’t exercise your way out of a bad diet’ or ‘Abs are made in the kitchen.’ But are those sayings true? How much does diet really impact body weight? And is it possible to lose weight without exercising?
We called on clinical dietitian Jessica Tilton to learn more about the factors that impact weight loss and how to lose weight without changing your activity level.
Learn if you need to lose weight
Tilton says Body Mass Index (BMI) is used to calculate whether an adult is at a healthy weight or has a high body weight.
Those with a BMI of 25 or higher are considered overweight. You can use a BMI calculator to find out where you land.
Tilton says excess body fat is causally linked to many health concerns. These include pulmonary disease, nonalcoholic fatty liver disease, gallbladder disease, hypertension, coronary heart disease, severe pancreatitis, certain cancers such as breast cancer and colorectal cancer, skin issues and gout.
Understand what factors impact weight loss
Losing weight is a challenging feat with instructions that can feel frustratingly simple.
“Weight loss requires consuming fewer calories than the body needs,” Tilton says.
Consuming fewer calories than the body burns, or a caloric deficit, leads to weight loss. Consuming more calories than the body burns leads to weight gain.
“Generally, people cannot exercise their way into weight loss,” she says.
This doesn’t mean you should avoid exercise. Instead, think of diet and exercise as a team that packs double the punch in supporting a healthy body.
Tilton says exercise has both physical and mental benefits that include improving brain health, strengthening bones and muscles, reducing the risk of disease, improving mood and helping with weight management.
“You really do want to do both because being sedentary is obviously not as healthy as being active," she says.
Determine how many calories your body needs
To determine if you are in a caloric deficit, you first need to know how many calories your body uses each day.
This can be done in a number of ways, but two options that Tilton suggests are the Total Daily Energy Expenditure and Resting Energy Expenditure formulas.
Total Daily Energy Expenditure and Resting Energy Expenditure calculators can be found online. They use factors such as gender, height and weight to provide daily calorie recommendations.
Resting Energy Expenditure estimates how many calories your body burns at rest.
Total Daily Energy Expenditure estimates how many calories your body burns depending on your typical activity level.
While nutritional needs look different for each person, Tilton says consuming 300 to 500 calories under your estimated total daily energy expenditure can help with weight loss.
It is important to lose weight in a way that is realistic and sustainable. Tilton says eating too few calories each day can lead to fatigue, muscle aches and possible essential vitamin and mineral deficiencies. If you need support and guidance in choosing a safe and effective weight loss plan, talk to your doctor or a licensed dietitian.
Additionally, cancer patients should discuss weight loss goals with their care team to avoid nutrient deficiencies and address how treatment may impact their efforts.
Monitor your calories and portions
“Diet is the most important factor in weight loss,” Tilton says.
To better understand your diet, she recommends keeping track of how many calories you are eating. There are a variety of fitness apps that can be helpful in tracking calories, or you can do it with a good old-fashioned paper and pen.
If you’d prefer not to track calories, it can be helpful to consider your portion sizes. If you notice you are eating more than your body needs to feel satiated, work toward smaller servings.
Choosing healthy, whole foods can aid in weight loss efforts by keeping you full and fueled.
MD Anderson dietitians recommend a diet primarily made up of healthy, nutritious foods. Aim for two-thirds of your diet to be made up of vegetables, whole grains, beans, fruits, nuts and seeds; the remaining third can be lean protein and dairy products.
Tilton says vegetables can make healthy snacks, and drinking more water helps the body feel full.
Of course, what you don’t eat can be just as important as what you do.
For those trying to lose weight, Tilton recommends cutting back on liquid calories, such as sugary beverages, beer and wine. She also suggests choosing fewer refined carbohydrates, fatty fried options and sweets.
While adjusting your diet and losing weight can be challenging, Tilton says that for those with a high body weight, losing even 5% to 10% of initial body weight can make a big difference in reducing some health risks.
“When people start losing weight, it’s naturally reinforcing. They start feeling better,” says Tilton. “They know ‘I can do this.’”