Weight loss tool • 2026 standards
\( \text{BMR} = 10 \times \text{Weight (kg)} + 6.25 \times \text{Height (cm)} - 5 \times \text{Age} + s \)
\( \text{TDEE} = \text{BMR} \times \text{Activity Factor} \)
\( \text{Calorie Deficit} = \text{TDEE} - \text{Calories Consumed} + \text{Calories Burned} \)
Where:
These formulas calculate daily calorie needs and deficits. A 500-calorie daily deficit typically results in ~1lb weight loss per week. The Mifflin-St Jeor equation is the most accurate for BMR calculation.
Example: For a 30-year-old male weighing 80kg, 180cm tall, moderately active:
\( \text{BMR} = 10 \times 80 + 6.25 \times 180 - 5 \times 30 + 5 = 1,740 \text{ kcal/day} \)
\( \text{TDEE} = 1,740 \times 1.55 = 2,697 \text{ kcal/day} \)
If consuming 2,000 kcal and burning 500 kcal exercising:
\( \text{Deficit} = 2,697 - 2,000 + 500 = 1,197 \text{ kcal/day} \)
This creates a 1,197 kcal/day deficit.
| Source | Calories | Contribution |
|---|
| Day | Exercise | Duration | Calories |
|---|
Calorie deficit occurs when you burn more calories than you consume. This fundamental principle drives weight loss. The body uses stored energy (fat) to make up the difference, resulting in weight reduction. A safe and sustainable deficit is typically 500-1000 calories per day.
Key formulas for calculating metabolic needs:
Where:
Approximate calories burned per hour for 70kg person:
Calories burned > calories consumed.
\( \text{Deficit} = \text{TDEE} - \text{Consumed} + \text{Burned} \)
Where deficit = energy gap for weight loss.
Calculating safe deficit levels.
What happens when you maintain a 500-calorie daily deficit?
The answer is B) You lose 1 pound per week. This is based on the fundamental principle that 1 pound of body fat contains approximately 3,500 calories. A 500-calorie daily deficit over 7 days equals 3,500 calories (500 × 7 = 3,500), which equals 1 pound of weight loss.
The 3,500-calorie rule is a fundamental concept in weight management. It's based on the energy density of adipose tissue. This calculation provides a theoretical framework for predicting weight loss. However, actual weight loss may vary due to metabolic adaptation, changes in lean body mass, and other factors.
Calorie Deficit: Calories burned exceed calories consumed
3,500-Calorie Rule: 3,500 calories = 1 pound of body fat
Energy Balance: Relationship between intake and expenditure
• 3,500 calories = 1 lb fat
• 500 cal/day = 1 lb/week loss
• Actual results may vary
• Combine diet and exercise for best results
• Track consistently for accuracy
• Be patient with results
• Expecting immediate results
• Not accounting for metabolic adaptation
• Ignoring lean body mass preservation
Calculate the BMR for a 28-year-old female who weighs 65kg and is 165cm tall using the Mifflin-St Jeor equation. Show your work.
Step 1: Identify the Mifflin-St Jeor formula for women
\( \text{BMR} = 10 \times \text{Weight (kg)} + 6.25 \times \text{Height (cm)} - 5 \times \text{Age} - 161 \)
Step 2: Substitute the values
\( \text{BMR} = 10 \times 65 + 6.25 \times 165 - 5 \times 28 - 161 \)
Step 3: Calculate each component
\( \text{BMR} = 650 + 1,031.25 - 140 - 161 \)
Step 4: Final calculation
\( \text{BMR} = 1,380.25 \text{ calories/day} \)
Therefore, the BMR is approximately 1,380 calories per day.
The Mifflin-St Jeor equation is considered the most accurate for calculating basal metabolic rate. It accounts for weight, height, age, and gender. BMR represents the calories needed at complete rest. TDEE (Total Daily Energy Expenditure) is calculated by multiplying BMR by an activity factor.
BMR: Basal Metabolic Rate - calories at rest
Mifflin-St Jeor: Most accurate BMR calculation method
TDEE: Total Daily Energy Expenditure
• Women: subtract 161 in formula
• Men: add 5 in formula
• BMR is at rest only
• Use kg for weight, cm for height
• Age affects metabolism
• TDEE = BMR × Activity Factor
• Using wrong gender constant
• Mixing up units (lbs vs kg)
• Confusing BMR with TDEE
A person has a TDEE of 2,400 calories per day. If they consume 1,800 calories daily and burn an additional 300 calories through exercise, what is their weekly calorie deficit? How much weight would they theoretically lose in a week?
Step 1: Calculate daily calorie deficit
Daily deficit = TDEE - Calories consumed + Calories burned
Daily deficit = 2,400 - 1,800 + 300 = 900 calories
Step 2: Calculate weekly calorie deficit
Weekly deficit = 900 × 7 = 6,300 calories
Step 3: Calculate theoretical weight loss
Weight loss = 6,300 ÷ 3,500 = 1.8 pounds
Therefore, the weekly deficit is 6,300 calories, theoretically resulting in 1.8 pounds of weight loss.
This problem demonstrates how both dietary restriction and exercise contribute to a calorie deficit. The exercise calories are added to the deficit because they represent additional energy expenditure beyond what's accounted for in TDEE. The calculation shows that combining diet and exercise can accelerate weight loss.
TDEE: Total Daily Energy Expenditure
Calorie Deficit: Energy gap for weight loss
Theoretical Loss: Based on 3,500-calorie rule
• Deficit = TDEE - Consumed + Burned
• Exercise adds to daily deficit
• 3,500 calories = 1 lb fat
• Combine diet and exercise for better results
• Track both intake and expenditure
• Consistency is key for progress
• Not accounting for exercise calories burned
• Forgetting to consider TDEE
• Expecting exact 3,500-calorie results
A person is consuming 1,800 calories daily with a goal of 30% protein, 40% carbohydrates, and 30% fat. Calculate the grams of each macronutrient they should consume daily. (Note: Protein = 4 cal/g, Carbs = 4 cal/g, Fat = 9 cal/g)
Step 1: Calculate calories per macronutrient
Protein: 1,800 × 0.30 = 540 calories
Carbohydrates: 1,800 × 0.40 = 720 calories
Fat: 1,800 × 0.30 = 540 calories
Step 2: Convert calories to grams
Protein: 540 ÷ 4 = 135 grams
Carbohydrates: 720 ÷ 4 = 180 grams
Fat: 540 ÷ 9 = 60 grams
Therefore, they should consume 135g protein, 180g carbs, and 60g fat daily.
This problem demonstrates macro distribution, which is important for preserving lean body mass during weight loss. Adequate protein intake (typically 0.8-1g per lb of body weight) helps maintain muscle mass. Carbohydrates provide energy for workouts, and fats support hormone production.
Macronutrients: Protein, carbs, and fat
Caloric Density: Calories per gram (4, 4, 9)
Macro Distribution: Percentage of calories from each macro
• Protein = 4 calories per gram
• Carbs = 4 calories per gram
• Fat = 9 calories per gram
• Higher protein preserves muscle
• Adjust macros based on activity
• Track consistently for accuracy
• Using wrong caloric values for macros
• Not accounting for protein needs
• Forgetting to verify total calories
Which of the following is TRUE about metabolic adaptation during prolonged calorie restriction?
The answer is B) Metabolism may decrease by 10-20% during dieting. Metabolic adaptation is a physiological response to reduced calorie intake. The body becomes more efficient, reducing energy expenditure to conserve resources. This adaptive thermogenesis can make continued weight loss more challenging over time.
Metabolic adaptation is an important concept in long-term weight management. As calorie intake decreases, the body responds by reducing energy expenditure through various mechanisms including decreased spontaneous activity, reduced thermic effect of food, and hormonal changes. This is why weight loss often slows down over time despite consistent efforts.
Metabolic Adaptation: Body's response to reduced calories
Adaptive Thermogenesis: Decreased energy expenditure
Energy Conservation: Body's protective mechanism
• Metabolism adapts to reduced calories
• Efficiency increases during dieting
• Weight loss may plateau over time
• Plan for metabolic adaptation
• Recalculate needs periodically
• Include refeed days if needed
• Not accounting for metabolic slowdown
• Expecting linear weight loss
• Giving up too soon during plateaus
Q: How accurate are the calorie burn estimates for different exercises?
A: Calorie burn estimates vary in accuracy based on several factors:
General Estimates: Within 10-20% accuracy for most activities
Individual Variations: Body composition, fitness level, and genetics affect actual burn
Measurement Methods:
The mathematical model for calorie estimation uses:
\( \text{Calories} = \text{MET} \times \text{Body Weight (kg)} \times \text{Time (hours)} \times 1.05 \)
Where MET (Metabolic Equivalent of Task) values are standardized but individual variations exist.
Q: What's the optimal macro distribution for weight loss while preserving muscle mass?
A: Research supports the following macro distribution for weight loss with muscle preservation:
Protein: 2.2-3.3 g per kg of body weight (higher end for resistance training)
Carbohydrates: 3-7 g per kg of body weight (depending on activity level)
Fat: 0.8-1.5 g per kg of body weight (minimum for hormone health)
For a 70kg person:
Studies show that higher protein intakes (2.2-3.3g/kg) during hypocaloric diets help preserve lean body mass. The total caloric intake should create a sustainable deficit while meeting protein requirements first.