Heading 1

What Is BMR and Why It Matters More After 40

The BMR calculator is a digital tool that helps you determine your basal metabolic rate. This is especially helpful after 40, as changes to lean body mass (LBM) can affect total daily energy expenditure (TDEE).

Below, we explore how BMR differs from TDEE and “calories burned”.

How BMR differs from TDEE and “calories burned”

Balancing calorie intake and energy expenditure can be confusing. While BMR and TDEE sound similar, they have different roles within nutrition.

As we know, BMR is the amount of calories the body burns at rest. Meanwhile, TDEE refers to your BMR and all “calories burned” throughout the day.

Sources show that TDEE includes:

• RMR: Calories the body burns at rest, accounting for 60–80% of total energy expenditure.

• Thermic Effect of Food (TEF): Calories burned during digestion and absorption, accounting for 10% of total energy expenditure.

• Physical Activity: This includes exercise and non-exercise energy expenditure (NEAT), which accounts for 20–50% of energy expenditure.

BMR Calculator for Women 40+ (Inputs and Outputs)

The BMR calculator provides information that can help you take measured steps toward achieving your exercise and nutrition goals. Below, we discuss the required inputs and expected output to highlight its function.

Required Inputs

The BMR calculator utilizes the following inputs to determine your BMR:

• Age: BMR declines with age due to a decrease in LBM (muscle, bone, and organs).
• Height: Influences energy expenditure. Great height means greater body mass, meaning greater BMR.
• Weight: Great weight means greater body mass and higher energy expenditure.
• Activity: Influences energy requirements, as those who are more active will burn more calories each day.
• Goals: This will be used to determine your goal-based macros, such as fat, body recomposition, and building muscle.

What You’ll Get

Following your inputs, the calculator will present you with the following results.

• BMR: Calories the body burns at rest and to maintain normal body function.
• Estimated Maintenance (TDEE): RMR, TEF, exercise, and NEAT.
• Goal-Based Starter Macros: Displays recommendations for calories, carbohydrates, protein, and fats based on your goals.

The Equations We Use (Explained Simply)

The BMR calculator utilizes common equations to determine your result. Below, we discuss the formula to show you how it is applied.

Mifflin–St Jeor (Default)

The Mifflin-St. Jeor equation is used to calculate the BMR. Below, we present the formula and an example.

• (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161 = BMR

Now we will calculate the BMR for a 44-year-old woman who weighs 75 kg and is 170 cm tall.

• (10 x 75) + (6.25 x 170 cm) - (5 x 44) - 161 = BMR
• 750 + 1062.5 - 220 - 161 = 1,431.5 kcal/day

From BMR to Maintenance Apply Activity Factors (sedentary → athlete)

Once you have received your BMR, you can calculate your TDEE to determine your maintenance calories. This is done by multiplying your BMR by the activity factor, which is a figure that corresponds to your level of physical activity.

Using the BMR from the example above, we will calculate maintenance calories.

Example:

• BMR x activity factor (moderate activity)
• 1,431.5 kcal x 1.55 = 2,218.8 kcal/day

Therefore, 2,218.8 kcal/day is needed to maintain weight with a moderately active physical activity level.

Use this for the initial 2–4 week time frame to track your weight, energy levels, and performance. If you notice a major dip in energy, poor performance, or you are unable to lose weight, consider recalculating and adjusting based on your goals.

Apply Your Number — Protein, Macros, and Goals

Once you have determined your TDEE for weight maintenance, you can now determine your macronutrient intake to match your goals. Below, we discuss the different goals and macro ratios to help you manipulate your nutrition for maximum success.

Choose A Goal

Here is a list of common goals that many women aim for over 40, including fat loss, body recomposition, and building muscle. Here, we discuss the best calorie intake and macronutrient recommendations for the greatest chance of success.

Fat Loss

This requires a calorie deficit, meaning that you consume fewer calories than your BMR. This allows you to burn fat even at rest.

During this process, protein is prioritized to help preserve muscle mass. Sources indicate that high-protein diets also increase fullness and thermogenesis, which is the energy required for digestion and absorption. This means less hunger between meals and increased energy expenditure.

• Calories: Calorie deficit
• Carbohydrates: 40% of daily calorie intake
• Protein: 30–35% of daily calorie intake
• Fats: 25–30% of daily calorie intake

Professional Tips

• Exercise, such as resistance training and walking, can be used to preserve muscle mass and increase energy expenditure.
• Weight loss may plateau. This can happen when body mass decreases, lowering BMR and TDEE, which can affect your calorie deficit. When this happens, recalculate your BMR and TDEE to determine your new calorie deficit.

Body Recomposition

Body recomposition refers to simultaneously building muscle and losing fat. Like fat loss, this requires a small calorie deficit and high protein intake; however, there is a great emphasis on resistance training to build muscle and daily steps.

Research shows long-term resistance training may result in an increase in 24-hour energy expenditure and fat oxidation. This highlights its ability to build muscle and burn fat. To take advantage of these benefits, you must be performing 2–4 resistance training sessions per week.

Alongside this, we recommend performing 7,000 steps/day to increase energy expenditure and burn fat.

• Calories: Small calorie deficit
• Carbohydrates: 40% of daily calorie intake
• Protein: 30% of daily calorie intake
• Fat: 30% daily calorie intake

Professional Tips

• Start with a small calorie deficit of 200–400 kcal/day and monitor progress.
• Weight may stay the same during initial weeks. This is because you will be building muscle and losing fat. After this, weight will decrease as a result of fat loss, revealing muscle.

Muscle Gain

Building muscle requires a calorie surplus. These additional calories will allow for greater protein and carbohydrate intake to fuel training sessions and build muscle.

Studies show that muscle hypertrophy occurs when muscle protein synthesis exceeds muscle protein breakdown. This is facilitated by resistance training and protein intake.

Sources recommend consuming a high-protein diet consuming 1.6–2.2 g/kg/day, 0.8–1.0g/kg of fat, with the remaining going to carbs. Combine this with 2–4 resistance training sessions per week.

• Calories: Calorie surplus (+5–10% from maintenance)
• Carbohydrates: 45–50% of daily calorie intake
• Protein: 25% of daily calorie intake
• Fats: 25–30% of daily calorie intake

Professional Tips

• Begin your hypertrophy training 2–3 times per week using a full-body training program.
• Increase training to 3–4 times a week and consider splitting your workout into upper and lower body sessions.

Midlife Considerations That Influence BMR

Women experience several challenges in midlife due to declining hormone levels. In this section, we explore different considerations that influence BMR after 40.

Lean Body Mass (Muscle, Bone, Organs, Water)

Lean body mass encompasses muscle, bone, organs, and water, which are all affected with age and menopause. The decreased mass of these metabolic tissues can result in lower resting energy expenditure.

• Muscle Mass: Sources indicate that muscle mass declines by 3–8% per decade.
• Bone Mass: Bone mass is shown to decline as estrogen decreases.
• Organs: Organs such as the brain, kidneys, and liver are shown to decrease with age, significantly decreasing resting energy expenditure.
• Water: Sources show that as muscle mass decreases, total body water declines.

NEAT

Non-exercise activity thermogenesis such as walking, performing chores, and other daily tasks substantially increase metabolic rate. However, as physical activity decreases, so too does energy expenditure, making it harder to sustain a healthy weight.

Sleep and Recovery In Peri/Postmenopause

Declining estrogen levels can affect sleep and recovery. Hormonal fluctuations can result in symptoms such as hot flashes, night sweat, anxiety, insomnia and muscle and joint aches and pains which can negatively impact sleep.

When sleep is impaired it can impact recovery, with sources showing that sleep deprivation can reduce protein synthesis. This decreases the ability to restore muscle damage.

Worked Examples (Follow Along)

Below, we have provided two working examples to show you how the BMR calculator, using the Mifflin–St Jeor equation and activity factor.

• (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161 = BMR

Example A

First example is for a sedentary 45-year-old women who want to lose weight:

• Goal: Fat loss
• Age: 45
• Height: 175 cm
• Weighs: 80 kg
• Activity Level: Sedentary (x 1.2)

Determine BMR

• (10 x 80) + (6.25 x 175) - (5 x 45) - 161 = BMR
• 800 + 1093.75 - 225 - 161 = 1507.75 kcal/day

Multiply by Sedentary Activity Factor

• 1507.75 x 1.2 = 1809.3 kcal/day

Macronutrient and Calorie Recommendations

• Calories: 1,500 kcal/day (307.75 kcal deficit)
• Carbohydrates: 40% (150 g)
• Protein: 30% (112 g)
• Fats: 30% (50 g)

Example B

The next example is for a moderately active 52-year-old woman who wants to build muscle:

• Goal: Build muscle
• Age: 52
• Height: 165 cm
• Weighs: 68 kg
• Activity Level: Moderately active (x 1.55)

Determine BMR

• (10 x 68) + (6.25 x 165) + (5 x 52) - 161 = BMR
• 680 + 1031.25 + 260 - 161 = 1810.25 kcal/day

Multiply by Active Activity Factor

• 1810.25 x 1.55 = 2805.88 kcal/day

Macronutrient and Calorie Recommendation

• Calories: 2805.88 kcal
• Carbohydrates: 50% (351 g)
• Protein: 25% (175 g)
• Fats: 25% (78 g)

Accuracy, Re-Testing, and When to Update

Tracking with the BMR calculator requires re-testing as your progress. This is because as you gain weight or lose fat, your body mass changes, altering your BMR, which can impact your calorie surplus or calorie deficit.

We recommend re-calculating every 4–6 weeks or any time your activity level or weight changes. This will ensure you are still progressing and maintaining the correct calorie balance for your goals.

Re-check Cadence and What Changes to Track (Waist/Hip, Strength, Energy)

Establishing baseline measurements of waist/hip, strength, and energy levels highlights your starting point. From here, you can re-check using the following format:

Check-in Frequency

• Beginners: Check-in every 4–6 weeks as body composition can change faster for beginners.

• Intermediate/Advanced: Check-in every 8–12 weeks as changes are more gradual.

• Tips: Test within the same condition such as time of day, before meals, with the same tape, and tester.

Areas to Track

• Waist & Hip Measurements: Indicates fat loss for the midsection and lower body.

• Strength Performance: Track strength lifts such as squats, presses, deadlifts, lunges, and plank. If your strength is being maintained or improving it likely means you are preserving LBM.

• Energy and Recovery: Recover energy levels, sleep, and recovery. This includes changes to training and nutrition.

• Before and After Photos: Taking photos at each check-in provides visual data of your progress.

• Clothing Fit/Size: Monitoring clothes size helps you see the progress and appreciate your hard work.

Sources

1. Manini TM. Energy expenditure and aging. Ageing Res Rev. 2010 Jan;9(1):1-11. doi: 10.1016/j.arr.2009.08.002. Epub 2009 Aug 19. PMID: 19698803; PMCID: PMC2818133. https://pmc.ncbi.nlm.nih.gov/articles/PMC2818133/
2. Manini TM. Energy expenditure and aging. Ageing Res Rev. 2010 Jan;9(1):1-11. doi: 10.1016/j.arr.2009.08.002. Epub 2009 Aug 19. PMID: 19698803; PMCID: PMC2818133. https://pmc.ncbi.nlm.nih.gov/articles/PMC2818133/
3. Kirk EP, Donnelly JE, Smith BK, Honas J, Lecheminant JD, Bailey BW, Jacobsen DJ, Washburn RA. Minimal resistance training improves daily energy expenditure and fat oxidation. Med Sci Sports Exerc. 2009 May;41(5):1122-9. doi: 10.1249/MSS.0b013e318193c64e. PMID: 19346974; PMCID: PMC2862249. https://pmc.ncbi.nlm.nih.gov/articles/PMC2862249/
4. Krzysztofik M, Wilk M, Wojdała G, Gołaś A. Maximizing Muscle Hypertrophy: A Systematic Review of Advanced Resistance Training Techniques and Methods. Int J Environ Res Public Health. 2019 Dec 4;16(24):4897. doi: 10.3390/ijerph16244897. PMID: 31817252; PMCID: PMC6950543. https://pmc.ncbi.nlm.nih.gov/articles/PMC6950543/
5. Stark M, Lukaszuk J, Prawitz A, Salacinski A. Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training. J Int Soc Sports Nutr. 2012 Dec 14;9(1):54. doi: 10.1186/1550-2783-9-54. PMID: 23241341; PMCID: PMC3529694. http://pmc.ncbi.nlm.nih.gov/articles/PMC3529694/
6. Volpi E, Nazemi R, Fujita S. Muscle tissue changes with aging. Curr Opin Clin Nutr Metab Care. 2004 Jul;7(4):405-10. doi: 10.1097/01.mco.0000134362.76653.b2. PMID: 15192443; PMCID: PMC2804956. https://pmc.ncbi.nlm.nih.gov/articles/PMC2804956/. https://pmc.ncbi.nlm.nih.gov/articles/PMC2804956/
7. Cheng CH, Chen LR, Chen KH. Osteoporosis Due to Hormone Imbalance: An Overview of the Effects of Estrogen Deficiency and Glucocorticoid Overuse on Bone Turnover. Int J Mol Sci. 2022 Jan 25;23(3):1376. doi: 10.3390/ijms23031376. PMID: 35163300; PMCID: PMC8836058. http://pmc.ncbi.nlm.nih.gov/articles/PMC8836058/
8. He Q, Heshka S, Albu J, Boxt L, Krasnow N, Elia M, Gallagher D. Smaller organ mass with greater age, except for heart. J Appl Physiol (1985). 2009 Jun;106(6):1780-4. doi: 10.1152/japplphysiol.90454.2008. Epub 2009 Mar 26. PMID: 19325028; PMCID: PMC2692775. https://pmc.ncbi.nlm.nih.gov/articles/PMC2692775/
9. Serra-Prat, M., Lorenzo, I., Palomera, E., Ramírez, S. & Yébenes, J.C. (2019). Total body water and intracellular water relationships with muscle strength, frailty and functional performance in an elderly population: A cross-sectional study. The Journal of Nutrition, Health & Aging, 23(1), 96–101. https://doi.org/10.1007/s12603-018-1126-3. https://www.sciencedirect.com/science/article/pii/S1279770723010436
10. Yang, D-F., Shen, Y-L., Wu, C., Huang, Y-S., Lee, P-Y., Er, N.X., Huang, W-C. & Tung, Y-T. (2019). Sleep deprivation reduces the recovery of muscle injury induced by high-intensity exercise in a mouse model. Life Sciences, 235, 116835. https://doi.org/10.1016/j.lfs.2019.116835. https://www.sciencedirect.com/science/article/abs/pii/S0024320519307623

‍