Calorie deficit - a safe way to lose weight

Alfred Chan, HK BioTek Nutritionist Intern

Losing weight has long been a trending topic for most of us. Not only aiming to establish a better body shape, but what’s also important is that to maintain a healthy body weight to avoid overweight or even obesity and its following health problems.

If you’ve ever tried to reduce weight, you’ve probably heard of calorie deficit.

What is a calorie deficit?

A calorie deficit is achieved once the consumption of calories, either from foods or beverages, is lower than the calories expend in a day. To compensate for the insufficient amount of energy intake, our body will start burning the stored fat. Over time, this calorie cut can contribute to weight loss.

Our body needs to burn a certain number of calories to carry out all its daily functions.

Percentage	Energy expenditure	Definition
60-70%	Basal energy expenditure (BEE)	Minimum number of calories needed for a resting body to keep the most basic life-sustaining functions such as breathing and blood circulation
60-70%	Resting energy expenditure (REE)	Calories needed to perform basic functions when the body is at rest or sleeping
10-20%	Thermic effect of exercise (TEE)	Calories involved in all physical activity of the body
10%	Thermic effect of food (TEF)	Calories required for digestion, absorption and metabolism of food
Total	Total Daily Energy Expenditure (TDEE)	Total Daily Energy Expenditure (TDEE)

*BEE and REE are often used interchangeably.

*The energies required varies depending on their: sex, age, physical activity levels, height, weight, and body composition.

How can we calculate the calorie needs?

Males
Age	Sedentary	Moderate	Active
19-20	2600	2800	3000
21-25	2400	2800	3000
26-35	2400	2600	3000
36-40	2400	2600	2800
41-45	2200	2600	2800
46-55	2200	2400	2800
56-60	2200	2400	2600
61-65	2000	2400	2600
66-75	2000	2200	2600
76+	2000	2200	2400

Females
Age	Sedentary	Moderate	Active
19-25	2000	2200	2400
26-30	1800	2000	2400
31-50	1800	2000	2200
51-60	1600	1800	2200
61+	1600	1800	2000

Therefore, a person can create their calorie deficit after aware of how many calories they need each day or week, by either eating fewer calories or increasing their activity levels, or both.

How much calorie deficit is enough to lose weight?

In general, one pound (lb.) of body fat consists of about 3,500 calories. Hence, a person who desires to lose 1 lb. of fat in a week would require eating 3,500 calories fewer, or 500 calories fewer per day, over that time. However, it is not advisable for a calorie deficit to exceed 7,000 calories (2 lb.) per week from a health concern.

Diet

Theoretically, as long as the calorie consumption is greater than the calorie intake, it can lead weight loss no matter what kind of food you eat. However, this approach does not take into account the nutrient density, which will affect your health. In addition, different food sources will also affect the body's hormones, metabolism, hunger and fullness, and ultimately the calorie intake. Therefore, one key in reaching a calorie deficit safely is altering the dietary habit by replacing certain higher calorie foods with lower calorie foods that are rich in nutrients.

Cut back on refined carbs such as sugary treats, fries and foods made with white flour, and replacing them with whole carbs that consist of more fiber and keep you satisfied, such as:

• Whole grains – whole wheat or multigrain bread, brown rice, barley, quinoa, bran cereal, oatmeal

• Non-starchy vegetables – spinach, green beans, Brussels sprouts, celery, tomatoes

• Legumes – kidney beans, peas, lentils

• Nuts – peanuts, cashews, walnuts

• Fruits – apples, berries, citrus fruit, bananas, pears

Eat adequate healthy proteins including lean meats, poultry, eggs, legumes, nuts, soy products, and seafood to reduce cravings about food.

Load your plate with large amount of leafy green vegetables each meal including broccoli, cauliflower, spinach, tomatoes, kale, brussels sprouts, cabbage, chard, lettuce and cucumber without greatly consuming calories

Eat good fats, such as olive oil, avocado oil, canola oil, or coconut oil. Don’t be afraid of eating fats. Your body still requires healthy fats no matter what kind of diets you adopt.

Avoid drinking sugary beverages like soda, fruit juices, and specialty coffee drinks that packed a significant number of calories.

Despite a calorie deficit is a vital part of weight loss, but it is not the whole picture. Other factors like genes, hormones, sleep quality, and medications can also influence weight.

Also, note that consuming too few calories can be risky to health. Set a sustainable and healthy goal and refer to your doctor’s or nutritionist’s recommendation if necessary.

References:

1. United States Department of Agriculture. (2015). 2015-2020 Dietary Guidelines for Americans (8th ed.). Retrieved from https://health.gov/sites/default/files/2019-09/2015-2020_Dietary_Guidelines.pdf

2. Frothingham, S. (2018). What Is Basal Metabolic Rate? Healthline. Retrieved from https://www.healthline.com/health/what-is-basal-metabolic-rate