Weight Loss Calculator

How to Calculate Weight Loss

Calculating weight loss involves estimating the number of calories needed to create a deficit and the time it will take to reach a target weight. Here's a comprehensive guide on how to perform these calculations:

Weight Loss Formula

The basic formula for calculating weight loss is based on the principle of calorie deficit:

$$\text{Weight Loss} = \frac{\text{Calorie Deficit}}{\text{Calories per kg of body fat}}$$

Where:

• Calorie Deficit is the number of calories reduced from maintenance level
• Calories per kg of body fat is approximately 7700 calories

Calculation Steps

1. Calculate Basal Metabolic Rate (BMR) using the appropriate formula based on gender.
2. Determine Total Daily Energy Expenditure (TDEE) by multiplying BMR with an activity factor.
3. Choose a desired weight loss rate (e.g., 0.5 kg per week).
4. Calculate the required calorie deficit based on the desired weight loss rate.
5. Subtract the calorie deficit from TDEE to get the total daily calorie intake for weight loss.
6. Calculate the time to reach the target weight based on the weight loss rate.

Example Calculation

Let's calculate the weight loss plan for a 30-year-old female, 165 cm tall, currently weighing 70 kg, with a target weight of 60 kg, moderately active, aiming to lose 0.5 kg per week.

Step 1: Calculate BMR

$$\begin{align} \text{BMR} &= 447.593 + (9.247 \times 70) + (3.098 \times 165) - (4.330 \times 30) \\ &= 1441.45 \text{ calories} \end{align}$$

Step 2: Calculate TDEE (using activity factor 1.55 for moderately active)

$$\begin{align} \text{TDEE} &= 1441.45 \times 1.55 \\ &= 2234.25 \text{ calories} \end{align}$$

Step 3: Calculate Calorie Deficit

$$\begin{align} \text{Calorie Deficit} &= 0.5 \text{ kg/week} \times \frac{7700 \text{ calories/kg}}{7 \text{ days/week}} \\ &= 550 \text{ calories/day} \end{align}$$

Step 4: Calculate Total Daily Calories for Weight Loss

$$\begin{align} \text{Total Calories} &= 2234.25 - 550 \\ &= 1684.25 \text{ calories} \end{align}$$

Step 5: Calculate Time to Reach Target Weight

$$\begin{align} \text{Time to Reach Goal} &= \frac{70 \text{ kg} - 60 \text{ kg}}{0.5 \text{ kg/week}} \\ &= 20 \text{ weeks} \end{align}$$

Therefore, this individual should consume approximately 1684 calories per day to lose 0.5 kg per week, and it will take about 20 weeks to reach the target weight of 60 kg.

Visual Representation

This bar chart illustrates the components of the daily calorie intake for weight loss in our example. The first bar shows the maintenance calories (TDEE), the second bar represents the calorie deficit needed for weight loss, and the third bar displays the total daily calorie intake required for the desired weight loss rate.