How Your Body Burns Calories and the 21 Day Fix Calorie-Controlled Diet Plan

How Your Body Burns Calories and Why It Matters

When it comes to weight loss and weight management, the concept of "calories in versus calories out" dominates much of the discussion. At its core, this idea states that to lose weight you simply need to burn more calories than you consume, creating a calorie deficit. To gain weight, consume more calories than you burn. This seems like a simple equation, but the reality is much more complex. Understanding how your body actually burns calories can help you create more effective diet and exercise plans to reach your goals.

What Does "Calorie Burn" Actually Mean?

Your body burns calories to fuel all of its basic functions, from keeping your heart beating to powering your lungs and digesting your food. The number of calories your body burns in a day is referred to as your Total Daily Energy Expenditure (TDEE). Your TDEE consists of three main components:

• Basal Metabolic Rate (BMR): Your BMR represents the minimum number of calories your body needs to perform essential functions like breathing and keeping your organs functioning. It makes up the largest portion, 50-70%, of your TDEE.
• Physical Activity: The energy you expend through movement and exercise makes up 20-30% of your TDEE. This includes not just formal exercise sessions but also non-exercise activity thermogenesis (NEAT) like walking, fidgeting, and completing household chores.
• Thermic Effect of Food (TEF): Digesting, absorbing, and metabolizing the food you eat accounts for around 10% of your TDEE. The TEF refers to the number of calories burned through this process.

Together these elements determine your total calorie burn for the day. When your calorie burn exceeds the number of calories you consume, you lose weight. Burn fewer calories than you eat, and you gain weight. That's the basic math behind calories in vs calories out. But that doesn't mean all calories are treated equal when it comes to your body's energy balance and ability to shed fat.

6 Factors That Impact How Many Calories You Burn

A number of variables affect how many calories your body burns each day. Some you have control over and some you don't. Being aware of these factors can help you understand your body better and dial in an eating and exercise plan that works for you.

1. Basal Metabolic Rate

As noted earlier, your basal metabolic rate accounts for the largest portion of your daily calorie burn. And BMR can vary significantly from person to person based on:

• Body size and composition - People with more muscle mass tend to have a higher BMR. Muscle is metabolically active tissue that burns more calories for energy even at rest compared to fat.
• Sex - Men naturally tend to have less body fat and more muscle mass than women as well as larger organ size, so BMR tends to be higher in men.
• Age - BMR declines gradually over time, typically dropping 5-10% per decade past age 30.
• Genetics - Some inherited factors can predispose you to having a faster or slower metabolism.

You have limited control over these elements, but being aware of how they impact your BMR can help you set appropriate calorie intake goals.

2. Physical Activity Level

Increasing your physical activity is one of the most effective ways to burn more calories. Adding cardio like running, biking, or swimming is a great strategy. But also look for opportunities to be more active throughout your normal daily routine with things like taking the stairs, walking or biking instead of driving short distances, doing yardwork, or adding short exercise breaks to your workday.

In addition to formal exercise, pay attention to your NEAT. Things like fidgeting, pacing, standing and overall movement require extra calories that can really add up over the course of a day. Finding ways to increase your general activity level can boost your daily calorie burn.

3. Muscle Mass

Adding more muscle through strength training is a popular recommendation for revving up your metabolism. Because muscle tissue is more metabolically active than fat, it helps increase the number of calories you burn at rest and during physical activity.

When you lift weights, do bodyweight exercises like push-ups and squats, or perform resistance exercises using bands, tubes, or machines, you break down muscle fibers. As they repair and grow back stronger, your muscles become larger and more defined.

This muscle building process, known as hypertrophy, increases your BMR. Many experts suggest strength training most days of the week to build metabolism-boosting muscle mass.

4. Thermic Effect of Food

The thermic effect of food refers to the calories you burn through the process of digesting, absorbing, transporting, and metabolizing the nutrients in your meals and snacks. Protein has the highest TEF, requiring 25-30% of the calories it provides just to digest it. Carbohydrates require 5-10% of their calories for digestion, while fat needs just 3-5%.

To take advantage of the TEF differences between macronutrients, many dietitians recommend emphasizing protein in your diet over carbohydrates and fat. Eating more protein-rich foods like meat, seafood, eggs, legumes, nuts and low-fat dairy can help increase your daily calorie burn from food.

5. Medical Conditions

Certain medical conditions can directly impact your resting metabolic rate and daily calorie burn. For example, an overactive thyroid (hyperthyroidism) speeds up metabolism, while an underactive thyroid (hypothyroidism) slows it down. Cushing's disease, polycystic ovarian syndrome (PCOS), and diabetes can also affect metabolic rate.

If you suspect you have any of these conditions, it's important to get an accurate diagnosis from your doctor. This allows you to understand how a medical issue may be impacting your body's calorie burn so you can adjust your diet and activity levels accordingly under your doctor's supervision.

6. Calorie Quality

When trying to lose fat, the mantra “a calorie is a calorie” isn’t entirely accurate. The source of calories matters for your body composition, hunger levels, and health.

For example, 100 calories from broccoli is not treated the same way by your body as 100 calories from soda. Whole, unprocessed foods like fruits, vegetables, lean proteins, whole grains and legumes require more energy to break down and absorb. They also provide more volume and take up more space your stomach, promoting fullness.

Meanwhile, highly processed fast foods, sugary beverages, refined carbs and salty snacks offer very little nutritionally once absorbed into your system. To maximize fat burning and weight loss, emphasize Whole, filling foods over processed products.

The 21 Day Fix: A Calorie-Controlled Program for Weight Loss

The 21 Day Fix is a popular commercial diet and exercise program claiming to help you “lose up to 15 pounds in 21 days.” It was created by celebrity fitness trainer Autumn Calabrese and emphasizes portion control through color-coded containers.

How the 21 Day Fix Works

The core component of the 21 Day Fix is dividing your meals into portion-controlled containers. The program provides seven color-coded containers that each hold a specified amount of food:

• Green container - 1 1/2 cups veggies
• Purple container - 1 1/2 cups fruit
• Red container - 1 1/2 cups proteins
• Yellow container - 1/2 cup carbs
• Blue container - 1/2 cup dairy
• Orange container - 2 1/2 tbsp seeds/dressings
• Teal container - 1/3 cup oils/nut butters

You fill your assigned number of containers with healthy foods to create balanced, calorie-controlled meals and snacks. The program claims this container system takes the guesswork out of portion sizes for easier weight loss.

In addition to the eating plan, the 21 Day Fix includes specific workout routines combining cardio and strength training. Each day features a 30 minute DVD with moves targeting upper body, lower body and core. You can adjust intensity by using different levels of weights.

FAQs

What is the thermic effect of food?

The thermic effect of food (TEF) refers to the number of calories your body burns through digesting, absorbing, and metabolizing the nutrients in your meals and snacks. Protein has the highest TEF.

How can I increase my NEAT?

Look for opportunities to be more active throughout your day with things like taking the stairs, walking or biking instead of driving short distances, doing yardwork, or adding short exercise breaks to your workday.

What are the components of the 21 Day Fix?

The 21 Day Fix includes portion control through color-coded containers as well as specific workout routines combining cardio and strength training.

How does muscle mass impact calorie burn?

More muscle mass increases your basal metabolic rate because muscle tissue burns more calories for energy than fat, even at rest.

What medical conditions can affect metabolic rate?

Conditions like hypothyroidism, hyperthyroidism, PCOS, Cushing's disease, and diabetes can all impact your resting metabolic rate and daily calorie burn.