How Your Plan Is Calculated

Your daily calorie target and your goal date are worked out from four steps: your basal metabolic rate, how active you are, the goal you chose, and, if you are losing weight, how long that takes. This page sets out each one, the equation behind it, and the research it comes from, so you can check the numbers yourself.

Every figure here is an estimate. Energy needs vary between people of the same age, sex, height and weight, so treat your target as a starting point to adjust from rather than a measurement.

Step 1: Your basal metabolic rate

Your basal metabolic rate (BMR) is roughly the energy your body uses at complete rest: breathing, circulation, keeping your organs running. It is the largest part of what you burn in a day, and everything else is built on top of it.

Welling uses the Mifflin-St Jeor equation:

Several equations exist for this. Welling uses Mifflin-St Jeor because a systematic review in the Journal of the American Dietetic Association compared the common ones against measured resting metabolic rate and found it most accurate for healthy adults, predicting within 10% of the measured value for about 82% of people, against roughly 69% for the older Harris-Benedict equation. [1][2]

Step 2: Your activity multiplier

BMR only covers being at rest. Multiplying it by an activity factor gives your total daily energy expenditure (TDEE), which is what you actually burn in a day, including moving around, working and exercising.

That factor is what nutrition research calls a physical activity level, or PAL: the ratio of what you burn in a whole day to what you burn at rest. A PAL of 1.5 means you use half again as much energy as you would lying still. [3]

The factor depends on how much you are on the move during a normal day. Welling asks which of three describes yours:

The middle and upper values are the ones the European Food Safety Authority uses for a low active and a moderately active lifestyle when it sets energy reference values for adults: PAL 1.4 and 1.6. [4] The lowest, 1.2, is the figure calorie calculators have long used for a desk-bound day; it sits below the range international bodies model for free-living adults, which makes it a conservative floor rather than a typical value.

These three run deliberately low. FAO/WHO/UNU puts office work in a sedentary or light bracket of PAL 1.40–1.69, and classes masons and construction workers as moderately active, PAL 1.70–1.99, above the 1.6 Welling assigns a hard physical job. [3] Erring low is the safer direction: it produces a smaller TDEE, so a weight-loss target lands at or below what you need rather than above it. The worked example below uses ×1.2 for the same reason.

This level describes your day, not your training. Many apps fold an exercise allowance into the daily target itself, so it assumes workouts even on the days you do none. Welling keeps the two apart: workout calories are added only when you actually log a workout.

Step 3: Your goal

Your TDEE is what holds your weight steady. What Welling does with it depends on which goal you chose.

Lose Weight

Losing fat requires eating less energy than you use, so Welling subtracts a daily deficit from your TDEE, defaulting to 500 calories per day. That matches the deficit prescribed in the AHA/ACC/TOS obesity guideline, which lists a 500 or 750 calorie daily deficit as one of the standard ways to set a weight-loss target. [5]

The resulting target is then held above a floor. It is never set below:

• 1,200 calories per day for women
• 1,500 calories per day for men

These are not arbitrary. The same guideline prescribes 1,200–1,500 calories a day for women and 1,500–1,800 for men as the standard calorie range for weight loss; Welling's floors are the bottom of each of those ranges. [5] Below them, it becomes difficult to meet protein, vitamin and mineral needs from ordinary food, and sustained under-eating tends to cost muscle alongside fat. The guideline also notes that very-low-calorie diets, under 800 calories a day, belong only in a medical setting with supervision, not in a self-directed plan. [5]

If subtracting 500 would put you under your floor, your target is raised back up to it. Your actual daily deficit is then smaller than 500, and your goal date moves out accordingly.

Keep Fit

This goal is weight maintenance, so there is nothing to add or subtract: your daily target is your TDEE. Eating roughly what you burn is what keeps your weight where it is. The number is not fixed for good, though: if your weight or your activity level changes, your TDEE changes with it, and so does the target.

Gain Muscle

Building muscle is tissue your body has to construct, and that costs energy beyond what you burn in a day, so Welling adds a 250 calorie surplus on top of your TDEE.

The surplus is deliberately small. A review of energy intake and resistance training found that a surplus does help build lean mass, but advised a conservative one, roughly 1,500–2,000 kJ a day or about 360–480 calories, precisely to limit how much of the gain arrives as fat. [6] Welling sits at the cautious end of that advice. Eating far above your TDEE does not build muscle proportionally faster; it mostly adds fat.

Calories are also only half of it. Muscle is built from protein, and the surplus does nothing on its own without resistance training and enough protein to support it. The International Society of Sports Nutrition puts that at 1.4–2.0 g of protein per kg of body weight per day for people who train. [7] A surplus eaten without training, or without enough protein, tends to be stored rather than used.

Step 4: Your goal date

This step applies to weight loss. To project a date, Welling converts your remaining weight into the energy it represents, using the widely used figure of 3,500 calories per pound of body weight (about 7,700 calories per kilogram). That figure comes from Wishnofsky, who estimated the energy density of the tissue lost during weight reduction. [8]

Your goal date is that many days counted forward from today, assuming you hold the deficit consistently.

A worked example

A 35-year-old man, 90 kg, 180 cm, sedentary, aiming for 80 kg:

1. BMR = (10 × 90) + (6.25 × 180) − (5 × 35) + 5 = 1,855 calories
2. TDEE = 1,855 × 1.2 = 2,226 calories
3. Daily target, depending on his goal:
   • Lose Weight = 2,226 − 500 = 1,726, above the 1,500 floor, so it stands
   • Keep Fit = 2,226
   • Gain Muscle = 2,226 + 250 = 2,476
4. Goal date, on the weight-loss target: 10 kg is 22 lb, or about 77,000 calories. At 500 a day that is 154 days, or roughly 22 weeks

For contrast, a 32-year-old woman at 70 kg and 165 cm has a BMR of about 1,410 and a TDEE of about 1,692. Subtracting 500 would give 1,192, below the 1,200 floor, so her target is set at 1,200 and her real deficit is 492 calories a day rather than 500.

Why your results may differ

The 3,500-calories-per-pound rule is a linear approximation, and real weight loss is not linear. As you get lighter you burn less, so the same intake produces a smaller deficit over time. Research modelling this properly has shown the linear rule overestimates how much you will lose over the long run, and real timelines usually run longer than a simple projection suggests. [9]

Other reasons your experience will vary:

• Individual variation. Two people matched on age, sex, height and weight can differ in resting metabolic rate by a few hundred calories a day.
• Water and gut contents. Early changes on the scale are substantially water, especially when carbohydrate intake changes. This moves the scale without changing fat.
• Adaptation. Sustained restriction tends to reduce both resting expenditure and spontaneous daily movement.
• Logging accuracy. A projection assumes the deficit is actually being held. Under-recording intake is common and it is the single largest source of drift between the plan and the outcome.

This is why the plan is worth recalculating every few weeks against your current weight, rather than following one number to the end.

References

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, February 1990. PMID 2305711
2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, May 2005. PMID 15883556
3. FAO/WHO/UNU Expert Consultation. Human Energy Requirements. FAO Food and Nutrition Technical Report Series 1. Food and Agriculture Organization of the United Nations, Rome, 2004. See Chapter 5, Table 5.3, for the classification of lifestyles by physical activity level. fao.org
4. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific Opinion on Dietary Reference Values for energy. EFSA Journal, 2013;11(1):3005. doi:10.2903/j.efsa.2013.3005
5. Jensen MD, Ryan DH, Apovian CM, Ard JD, Comuzzie AG, Donato KA, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation, June 2014. PMID 24222017
6. Slater GJ, Dieter BP, Marsh DJ, Helms ER, Shaw G, Iraki J. Is an energy surplus required to maximize skeletal muscle hypertrophy associated with resistance training? Frontiers in Nutrition, 2019. PMID 31482093
7. Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017. PMID 28642676
8. Wishnofsky M. Caloric equivalents of gained or lost weight. The American Journal of Clinical Nutrition, September–October 1958. PMID 13594881
9. Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. The Lancet, August 2011. PMID 21872751

This page describes how Welling estimates a calorie target and a goal date. It is general information, not medical advice. If you are pregnant or breastfeeding, managing a medical condition, taking medication that affects appetite or metabolism, or have a history of disordered eating, speak to a healthcare professional before following a calorie target.