Weight Gain Calculator

How to Calculate Weight Gain

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

Weight Gain Formula

The basic formula for calculating weight gain is based on the principle of calorie surplus:

$$\text{Weight Gain} = \frac{\text{Calorie Surplus}}{\text{Calories per kg of body weight}}$$

Where:

• Calorie Surplus is the number of extra calories consumed above maintenance level
• Calories per kg of body weight 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 gain rate (e.g., 0.5 kg per week).
4. Calculate the required calorie surplus based on the desired weight gain rate.
5. Add the calorie surplus to TDEE to get the total daily calorie intake for weight gain.
6. Calculate the time to reach the target weight based on the weight gain rate.

Example Calculation

Let's calculate the weight gain plan for a 30-year-old male, 180 cm tall, currently weighing 70 kg, with a target weight of 80 kg, moderately active, aiming to gain 0.5 kg per week.

Step 1: Calculate BMR

$$\begin{align} \text{BMR} &= 88.362 + (13.397 \times 70) + (4.799 \times 180) - (5.677 \times 30) \\ &= 1791.5 \text{ calories} \end{align}$$

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

$$\begin{align} \text{TDEE} &= 1791.5 \times 1.55 \\ &= 2776.8 \text{ calories} \end{align}$$

Step 3: Calculate Calorie Surplus

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

Step 4: Calculate Total Daily Calories for Weight Gain

$$\begin{align} \text{Total Calories} &= 2776.8 + 550 \\ &= 3326.8 \text{ calories} \end{align}$$

Step 5: Calculate Time to Reach Target Weight

$$\begin{align} \text{Time to Reach Goal} &= \frac{80 \text{ kg} - 70 \text{ kg}}{0.5 \text{ kg/week}} \\ &= 20 \text{ weeks} \end{align}$$

Therefore, this individual should consume approximately 3327 calories per day to gain 0.5 kg per week, and it will take about 20 weeks to reach the target weight of 80 kg.

Visual Representation

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