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A Scientific Approach to Healthy Weight Loss

A Scientific Approach to Healthy Weight Loss

In this article we take a look at how science can help you approach your weight loss goals more effectively.

by Alexander Stone, DPT

Are you looking to shed a few pounds and wondering if understanding the science of weight loss can help you achieve your goals more easily? The answer is a resounding "Yes!" 

Contrary to popular belief, the science behind weight loss is not as complicated as it may seem. By gaining a basic understanding of the principles involved, you can make informed decisions and develop strategies that support your weight loss journey. 

Key Points

  • create a calorie deficit by consuming fewer calories than you burn.
  • prioritize whole, nutrient-dense foods
  • ensure an adequate protein intake to support muscle growth and satiety
  • use cardio to actively burn extra calories 
  • use strength training to build lean muscle mass, increasing your daily calorie burn, even while at rest
  • some supplements can help with fat metabolism and protein consumption
  • consistency is key

In this article, we will explore the fundamental aspects of weight loss, from the role of calories to the importance of exercise and supplements. So, let's dive in and uncover the science behind shedding those extra pounds!

What's a Calorie?

To understand the science of weight loss, it's important to start with the concept of a calorie. A calorie is a unit of energy that measures the amount of energy released when food is burned or metabolized by the body. It represents the energy required to raise the temperature of one gram of water by one degree Celsius. In simple terms, calories are the fuel that our bodies need to function properly.

Let’s start by talking about the three main types of macronutrients:

  • Carbohydrates are one of the primary macronutrients and are a key source of energy for the body. They provide around 4 calories per gram. Foods rich in carbohydrates include grains, fruits, vegetables, and legumes.
  • Proteins are essential for building and repairing tissues in the body. They also play a role in various metabolic processes. Like carbohydrates, proteins provide around 4 calories per gram. Good sources of protein include lean meats, poultry, fish, eggs, dairy products, and plant-based sources such as beans, lentils, and tofu.
  • Fats are another important macronutrient and are necessary for absorbing certain vitamins, providing insulation, and protecting organs. They have a higher calorie content, providing around 9 calories per gram. Healthy sources of fats include nuts, seeds, avocados, olive oil, and fatty fish.

Understanding the calorie content of different macronutrients is essential because it helps us make informed choices about our diet. By understanding the energy value of the foods we consume, we can better manage our calorie intake and create a balanced diet that supports our weight loss goals (1).

Now that we have a solid understanding of calories and macronutrients, let's explore how the balance between calories in and calories out influences weight loss.

Calories In, Calories Out

The principle of energy balance is fundamental when it comes to weight loss. It revolves around the concept of calories in versus calories out. Let's take a closer look at what this means and how it affects our ability to lose weight:

Calorie Deficit for Weight Loss

  • To lose weight, we need to create a calorie deficit, which means consuming fewer calories than we burn (2).
  • When we consistently maintain a calorie deficit, our bodies need to find alternative sources of energy to make up for the shortfall.
  • One of the primary sources of energy is body fat. As our bodies tap into stored fat, we gradually lose weight.

Calorie Surplus for Weight Gain

  • Conversely, when we consume more calories than we burn, our bodies store the excess energy as fat, resulting in weight gain (3).
  • This excess energy is stored for later use when our bodies need it.

Factors Affecting Energy Balance

While the concept of calories in versus calories out is crucial, it's essential to note that other factors influence weight management, such as hormones, genetics, and metabolism (4).

Hormones play a significant role in regulating hunger, satiety, and metabolism. Imbalances or changes in hormone levels can impact weight loss efforts.

Metabolism refers to the processes that occur in our bodies to convert food into energy. Some individuals may naturally have faster or slower metabolisms, affecting how their bodies utilize and store calories.

Understanding energy balance helps us make informed decisions about our diet and lifestyle. By creating a calorie deficit, we encourage our bodies to utilize stored fat for energy, leading to weight loss. However, it's crucial to approach weight loss in a sustainable and balanced manner, focusing on overall health and well-being.

How to Lose Weight Scientifically

When it comes to weight loss, it's important to understand the science behind it and the factors that influence whether we lose or gain weight. Two crucial numbers that play a significant role in weight management are our basal metabolic rate (BMR) and total daily energy expenditure (TDEE).

Basal Metabolic Rate (BMR)

  • Basal metabolic rate (BMR) refers to the number of calories your body needs to perform basic functions at rest. These functions include breathing, circulating blood, and maintaining body temperature (5).
  • BMR accounts for the largest portion of your daily calorie expenditure, usually representing around 60-75% of your total energy needs.

Factors that influence your BMR include age, gender, body composition, and genetics. Generally, individuals with more lean muscle mass tend to have a higher BMR as muscle requires more energy to maintain compared to fat.

Total Daily Energy Expenditure (TDEE)

  • Total daily energy expenditure (TDEE) represents the total number of calories you burn in a day, taking into account your BMR and physical activity level (6).
  • TDEE includes not only the calories burned during exercise but also the energy expended through daily activities, such as walking, cleaning, and even digesting food.

Physical activity level is an important factor in determining your TDEE. Those with more active lifestyles will have a higher TDEE compared to individuals with sedentary lifestyles.

To lose weight, it is crucial to create a calorie deficit. This means consuming fewer calories than your body needs, resulting in your body tapping into stored fat for energy.

The most effective way to create a calorie deficit is by combining a reduction in calorie intake and an increase in calorie expenditure through exercise.

Aiming for a calorie deficit of 500-1,000 calories per day is generally considered safe and sustainable. This can result in a steady weight loss of 1-2 pounds per week, which is a healthy rate of weight loss (7).

Calculating BMR and TDEE

  • To determine your BMR and TDEE, you can use online calculators that take into account factors such as age, gender, weight, height, and activity level.
  • These calculators provide estimates, and individual variations may exist. However, they serve as a useful starting point for understanding your calorie needs.

Once you have calculated your BMR and TDEE, you can adjust your calorie intake to create a calorie deficit. This can be achieved by reducing your calorie consumption or increasing your calorie expenditure through physical activity.

It is essential to approach calorie reduction with a balanced and sustainable mindset. Severely restricting calories can be detrimental to your health and may lead to muscle loss and a slower metabolism.

Aim for a gradual and modest calorie deficit, focusing on nutrient-dense foods and maintaining a well-rounded diet that supports overall health and well-being.

The Role of Exercise in Weight Loss

When it comes to weight loss, incorporating exercise into your routine offers numerous benefits beyond creating a calorie deficit through diet alone. Exercise not only burns calories during physical activity but also has a lasting impact on your metabolism, helping you achieve your weight loss goals more effectively. Let's explore the role of exercise in weight loss and the different types of exercises that can maximize calorie burn and boost your metabolism.

Calorie Burn During Exercise

  • Engaging in physical activity burns calories, contributing to your overall calorie expenditure for the day.
  • Cardiovascular exercises, such as running, cycling, swimming, and brisk walking, are popular choices for burning calories. These activities elevate your heart rate, increase oxygen consumption, and help you burn a significant number of calories during the workout (8).
  • The intensity and duration of your exercise session will determine the number of calories burned. Higher-intensity exercises, such as interval training or high-intensity interval training (HIIT), can provide a greater calorie burn in a shorter amount of time compared to steady-state cardio.

Post-Exercise Calorie Burn (EPOC)

  • One of the unique benefits of exercise is the post-workout calorie-burning effect known as excess post-exercise oxygen consumption (EPOC) or the afterburn effect (9).
  • After an intense workout, your body requires additional oxygen to restore energy stores, repair damaged tissues, and return to its pre-exercise state. This process involves an increased metabolic rate, which results in the burning of additional calories even after you've finished exercising.
  • The duration and intensity of the exercise session can influence the magnitude and duration of the EPOC effect. Higher-intensity exercises and activities that engage multiple muscle groups tend to result in a more significant EPOC effect.

Strength Training and Metabolism

  • While cardiovascular exercises are commonly associated with calorie burning, strength training is equally important for weight loss.
  • Strength training involves resistance exercises using weights, resistance bands, or bodyweight exercises. These exercises focus on building and strengthening your muscles.
  • Building lean muscle mass through strength training has a profound effect on your metabolism. 

Muscle tissue is metabolically active, meaning it requires more energy (calories) to maintain compared to fat tissue. By increasing your muscle mass, you raise your basal metabolic rate (BMR), which is the number of calories your body needs at rest.

Additionally, strength training promotes muscle growth, which contributes to a toned appearance and helps prevent muscle loss during weight loss. This is important as preserving muscle mass supports overall strength, mobility, and functional abilities.

A Balanced Approach

  • To maximize your weight loss efforts, it's important to include both cardiovascular exercises and strength training in your fitness routine.
  • Cardiovascular exercises help burn calories during the workout and contribute to the overall calorie deficit.
  • Strength training, on the other hand, enhances muscle growth, increases metabolism, and helps you burn more calories throughout the day, even at rest.

Aim for a well-rounded approach that includes a combination of cardiovascular exercises (such as running, cycling, or swimming) and strength training exercises (such as weightlifting, bodyweight exercises, or resistance band workouts).

Remember, exercise should be enjoyable and sustainable. Find activities that you enjoy and that fit into your lifestyle to ensure long-term adherence.

How to Use Supplements for Weight Loss

While a healthy diet and regular exercise form the cornerstone of successful weight loss, some individuals may consider incorporating supplements to support their efforts. It's important to approach supplements with caution, understanding their role and consulting with a healthcare professional before incorporating them into your routine. Let's explore the role of supplements in weight loss and the responsible ways to use them.

Supplements for weight loss are designed to complement a healthy lifestyle that includes proper nutrition and regular exercise. They are not magic pills or substitutes for healthy habits.

One commonly used supplement for weight loss is caffeine. Caffeine acts as a stimulant, increasing energy expenditure, and reducing appetite. It can give you a temporary energy boost and may help you feel more alert during workouts.

Other supplements that are sometimes used for weight loss include green tea extract and conjugated linoleic acid (CLA). These supplements are believed to have various effects on metabolism, appetite, or fat metabolism. However, their effectiveness and safety may vary, and research in these areas is ongoing (10).

It's essential to use supplements responsibly and with proper guidance. Before incorporating any supplement into your routine, consult with a healthcare professional, such as a registered dietitian or doctor, who can provide personalized advice based on your individual needs and health status.

Your healthcare professional can assess your overall health, review any potential interactions with medications you may be taking, and guide you on proper dosage and usage.

It's important to remember that supplements are not regulated as rigorously as medications, and their safety and effectiveness may vary. Therefore, consulting with a professional can help you make informed decisions.

While supplements may support your weight loss efforts, it's crucial to remember that they are not a substitute for healthy eating and regular exercise.

  • Focus on building a foundation of balanced nutrition, emphasizing whole foods, and meeting your nutrient needs through a varied diet.
  • Prioritize consuming nutrient-dense foods, such as fruits, vegetables, lean proteins, whole grains, and healthy fats, to provide your body with essential nutrients for overall health and well-being.
  • Engage in regular exercise that includes both cardiovascular exercises and strength training to maximize your weight loss potential.

Supplements, if used, should be seen as an additional tool that complements your healthy lifestyle choices.

Putting It All Together

Now that we've explored the key elements of weight loss, let's put it all together into a simple strategy. 

To achieve weight loss, focus on creating a calorie deficit by consuming fewer calories than you burn. Prioritize whole, nutrient-dense foods and ensure an adequate protein intake to support muscle growth and satiety. 

Incorporate a combination of cardio and strength training exercises to burn calories and build lean muscle mass. 

Remember that consistency is key, and finding activities you enjoy will make it easier to stick to your routine. Lastly, if you choose to use supplements, do so under the guidance of a healthcare professional.


Understanding the science of weight loss can empower you to make informed decisions and develop effective strategies to achieve your goals. By grasping the concept of calories, energy balance, and the role of exercise and supplements, you can embark on a weight loss journey with confidence. 

Remember, weight loss is a gradual process that requires consistency, patience, and a focus on sustainable habits. So, take the knowledge gained from this article and embark on your path to a healthier you!

About the Author:


Alex Stone is a Doctor of Physical Therapy and Certified Strength and Conditioning Specialist. He is experienced in orthopedics and sports medicine with an emphasis on performance optimization.

Alex creates educational content for apps, websites and social media (@dr.alexstone). He is passionate about health science education, exercise science, and general health/wellness optimization.


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