The best weight loss calculator (Pacer Coach uses it too)

The Pacer Coach’s weight loss planning calculator, based on the NIH Body Weight Planner, takes into account your activity level, resting metabolic rate and the effect on your metabolism as you eat less and lose weight. If you’re walking for weight loss, using a weight loss calculator will give you the most accurate predictions to ensure that you stay on schedule and meet your weight loss goals. Perhaps the best weight loss planner is the NIH Body Weight Planner, which takes into account your activity level, resting metabolic rate and the effect on your metabolism as you eat less and lose weight.

Even if your goal isn’t weight loss, it’s great to know many calories you need to eat and burn walking to maintain your current weight. This can help prevent you from getting stuck on a weight loss plateau, even if you manage to hit 10,000 steps per day. A good rule of thumb is 3,500 calories burned per pound lost, but the NIH weight loss calculator takes into account more info about how your body responds. Here’s where our Pacer Coach weight prediction comes from and how you can use it.

Get Pacer! If you don’t have Pacer yet, download Pacer for FREE! (on mobile)

**Note: Our Pacer Coach is a premium feature. You can try Premium free for 7 days to test it out, or you can use the Body Weight Planner here and estimate the activity measurements.

NIH Body Weight Planner

Doctor and woman looking over weight loss plan
Africa Studio / Shutterstock

The NIH Body Weight Planner was created by Dr. Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the NIH. Officially released in 2011, it was originally designed as a research tool but it was so useful that researchers decided to release it to the public.

It takes into consideration your current height, weight, age, sex and other information, as well as your goal weight and your target date for hitting that goal weight. It also takes into account your activity level as one of the most important factors. The planner is based on NIH science and has been validated by a two-year calorie-controlled study on 140 people that showed that the model was able to predict weight loss over time.

The planner also takes into consideration your responses to how much activity you’re willing or able to do and how many calories you can reduce from what you eat. If you’re physically unable to burn 500 extra calories per day, it wouldn’t make sense for that to be part of the recommendation. If you just can’t hit that goal, you’d be better off trying something else, like walking 1 extra mile and burning 100 calories while eliminating a bottle of soda a day. One reason the NIH Body Planner is such a powerful weight loss calculator is that it attempts to give you a plan that you’re actually willing to follow, which is key for weight loss.

Why does it work?

Weight loss methods concept
Stock-Asso / Shutterstock

If you’re looking to lose weight, you’ll need to reduce calories taken in, burn more calories through activity or use a combination of both of these methods. The general rule of weight loss is that you’ll need to burn 3,500 Calories to lose a pound of weight. This is based on the amount of energy released by a pound of fat (in a lab setting). Based off this model, if you create a calorie deficit of 500 calories per day (burning more, eating less or both), that’s 3,500 calories in a week and you’ll lose 1 pound.

As you lose weight, however, your body will respond in various ways that actually reduce the effectiveness of your calories burned. This doesn’t mean that it’s impossible to lose weight by getting active and eating less, but that weight loss may take you longer or require more of a reduction than you might expect. As Dr. Hall himself points out, up to half of the calorie deficit you create is lost (see why later in the piece).

This means that you may only see half a pound of weight loss for those 3,500 calories burned instead of the pound you expect. Or to put it another way you may need 7,000 calories of burn/reduction to lose the one pound. That’s totally fine, because gradual weight loss through small lifestyle changes is the best way to lose weight and keep it off long-term.

The model has created some interesting insights. It found that heavier people can lose weight faster, and it also can help people understand how their height, weight, age, sex and more can affect how difficult it will be to lose weight.

What factors go into the weight loss calculator?

Group of people running together for fitness
Jacob Lund / Shutterstock

You’ll be asked to input your height, weight, age, sex, and estimated activity level. You’ll select activity level based on your answers to 2 basic questions about your work and leisure activity level.

Next, you’ll input your goal weight and the time it takes to get there, followed by how much you plan to increase your activity as part of your weight loss calculations. Your increase in activity has an effect of how many calories you’ll reduce going forward. The model then spits out your results, and you can also see a graph of estimated progress over time.

There are some advanced controls where you can input things like body fat &, resting metabolic rate and more. If you know those they can make a small difference in the results but you can easily skip them and not have a huge impact on your results.

The physical activity modifier is only an estimate, but it has a huge impact on your projected calorie budget and weight loss. You’ll want to be as accurate as possible. Your activity level is assigned a modifier, from 1.4 for sedentary and 2.5 for extremely active. Pacer calculates this automatically based on your step count, which is a good proxy for how active you are. You’ll also want to be honest about how much physical activity you can do. Overestimating this will lead to a smaller calorie reduction. If you can’t follow through, you won’t hit your goals.

Why people often plateau

Tired female walker
Jacob Lund / Shutterstock

The larger you are, the more calories your body burns – both during exercise and at rest. There’s more mass to move around, and your body has to work harder. This is true whether you’re simply taller or if you have a higher amount of body fat.

This means, however, that as you lose weight you actually burn fewer calories. Your 30-minute walk will still be great for your health, but the number of calories you burn will decrease – at least slightly. The base amount of calories you need to maintain your weight also drops.

Cutting 50 calories per day will lead to some amount of gradual weight loss, but going from 2,000 calories to 1,950 will not cause your weight to eventually dwindle to zero. The NIH body planner takes this into account to ensure that you hit your goal over time.

Your body also has built-in survival mechanisms to ensure that you get enough nutrition. If it senses that your calorie intake has dropped, it can respond in a variety of ways. For one, you may feel hungrier. You can over being a bit more hungry and that doesn’t mean you’ll necessarily gain weight, but it’s one reason many people have difficulty maintaining weight loss over time. The more dramatically you cut calories, the hungrier you may feel.

Being at a calorie deficit also causes your metabolism to slow. That doesn’t mean it will slow to zero, and it doesn’t mean that it’s permanent. It does mean that a given weight loss plan may be less effective over time. Some studies have indicated that extremely rapid, extreme weight loss (Biggest Loser style) can cause long-lasting or permanent damage to your metabolism. There are older studies that seem to contradict this, but in any event, you’re very unlikely to be successful with crash dieting. Even relatively mild diets can cause some small changes in metabolism, which the NIH model accounts for.


Man checking watch running late
Mangostar / Shutterstock

A 180 pound, 5’7″ male, age 35 wants to reach a goal weight of 160 pounds in a year (365 days). He’s lightly active, both at work and in leisure time, and is willing to increase his physical activity by 10%. In addition to the activity boost, he should eat:

  • To maintain current weight: 2,739 Cal/day
  • To reach 160 pounds in 365 days: 2,485 Ca/day
  • To maintain 160 pounds in future: 2,601 Cal/day

An important note is that this person has increased their calories burned through activity, which means that they only need part of the reduction through calories burned. If they were even more active, these numbers would change.

You can use expert mode to get a nifty chart like this:

Body weight calculation chart

Pacer Coach

Active jogging woman checking phone
Martin Novak / Shutterstock

When you start our Pacer Coach’s weight loss calculator, we’ll use the height, weight and other data that you input into your Pacer app. If you haven’t input this data, we’ll prompt you to input it to get a more accurate estimate. Pacer will also estimate your activity level based on your recent steps which is a good proxy for how active you are. Finally, Coach will get your feedback on how much activity and calorie reduction you’re comfortable with or able to do.

Based on this information, Coach will give you activity and calorie goals as well as a projection of what your weight may look like over time. It also includes a range of weights, which reflects how everyone reacts to weight loss differently and not everyone is able to realistically stick to the plan.

As you log your weight into Pacer and update Coach on your progress, your projections will be updated and you’ll receive updated recommendations. You can also change your plan if you’re not able to meet the goals set.

Once you have solid recommendations, a graphed projection of your progress, and motivational reminders from the Pacer Coach you’ll be much more likely to hit your goals. You can try Coach for free as part of a 7-day trial of Pacer Premium. Or you can try to estimate this information at the NIH Body Weight Planning website. Good luck, and we hope that Pacer is able to help you reach your health, fitness, and weight loss goals.

Get Pacer

If you haven’t downloaded the Pacer app yet, download Pacer for free (on mobile)! You can also check out our website (mobile or desktop) or follow our blog for more great walking and healthy lifestyle tips.

4 thoughts on “The best weight loss calculator (Pacer Coach uses it too)

Leave a Reply