The Best Online
Calorie Calculator,
According to Science.
But it might not work for you.

Another free online calorie calculator, the Body Weight Planner, is now available to the public after several years of being used as a research tool for scientists at the National Institutes of Health. This one is noteworthy because its algorithms were validated in several controlled weight loss studies in human beings, and because it takes into account a person's slowing metabolism.
 
Kevin Hall, a scientist at the NIH's National Institute of Diabetes and Digestive and Kidney Diseases, created the tool.

Dr. Hall says the 3,500-calorie rule is accurate only if a pound of human fat is burned in a lab.  However, unlike a lab, the body is not a static environment, and instead adapts when a person changes their diet and exercise.

As a person diets and loses weight, the body slows the metabolism in an effort to conserve energy. As a result, eating 500 fewer calories a day leads to slightly less weight loss as time goes on.

Instead of 3,500 fewer calories, over 12 months, a person will need to eat 7,000 fewer calories to burn a pound of fat.

Dr. Hall said that the biggest flaw with the 3,500-calorie-rule is that it assumes weight loss will continue in a linear fashion over time. "That's not the way the body responds. The body is a very dynamic system, and a change in one part of the system always produces changes in other parts.”

He admits that dieters may be “bummed out” by news that they must double their efforts at reducing calories. “But we believe it's better to have an accurate assessment of what you might lose, that way you don't feel like a failure if you don't reach your goal.”

Dr. Hall added that very few people seem to be able to keep losing weight after 12 months.

The BWP calculates how many calories a day a person should eat to achieve their weight loss goals in a certain time (for example, to lose 10 lbs within a year).  The link can always be found here in DietHobby, under RESOURCES, Links, Body weight Calculator - NIH (Timeline Projections).

The NIH bills the planner as a cutting-edge tool that will empower people to take their health into their own hands, but research on the success of such calculators and trackers is mixed.  Although the federal government is to be praised for its official nod toward the utility of trackers and calculators,  human beings themselves are not “simple machines” who operate on a calories in, calories out basis.
 

The issue of Projections about the Rate of Weight-Loss has been on my mind for a very long time, and so this article is going to be quite long and detailed.  Those who bear with me and press on through, might learn some helpful information, or at least be exposed to something other than empty promises.

The Diet Industry knows that people want to lose their excess fat ASAP, and that people also want to spend as little time possible on a weight-loss Diet.  It takes advantage of that fact by using the diet-of-the-moment’s maximum 1st week weight-loss number as a marketing tool. 

Typical is: “Lose 15 pounds in 7 days”; or 10 pounds or 7 pounds, etc.  We see that ploy used continually in the media.  It is almost impossible to look at any magazine display rack in a supermarket checkout line without seeing a similar Headline.

What is implied by this claim is that the number of the first week’s weight loss is a prediction of weight-loss for the subsequent weeks. Marketing claims: “10 pounds in 1 week”.  People think, “Wow, If I stick to this Diet for just 5 weeks, I can lose 50 pounds.” 

Then, when they don’t experience that rate of weight-loss, they feel disappointed. Upon expressing their disappointment to the medical doctor, the nutritionist, the diet guru, the group leader, the program counselor, or whoever, the most common response is: “YOU didn’t follow the diet correctly.”  People are blamed for their weight-loss failure; while the Diet Industry gets the credit for their weight-loss success.

This is universal. I’ve never seen or participated in ANY diet program that didn’t follow that line of thinking, and during the past 60 years …from adolescence on… I’ve been involved with a great many of them.  I have personal experience with a great many diets and diet programs, and I’ve closely watched the experiences of many hundreds of other people as they dieted.

People WANT TO BELIEVE the claims of rapid weight-loss that they hear, and they desperately hope that they will personally experience rapid weight-loss by following their latest Diet-of-choice.   Some of these rapid weight-loss claims are based on lies; some are based on ignorance; some are based on personal experience together with poor memory; and a few are based on the real results of very unusual people. There are those who make these incorrect rapid weight-loss projections in good faith; who stubbornly hold onto an unreasonable Belief by stubbornly ignoring the overwhelmingly-vast-weight-of-the-evidence stacked up against it. However, the fact is that almost all of those claims are false, and the rest of them are based on factors that...

A Scientific Study was recently published concluding that an alternate-day fasting diet was NOT superior to a daily calorie restriction diet for Metabolically Healthy Obese Adults with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease (including insulin resistance).

The lead researcher in this study, Dr. Krista Varady, has previously done extensive research on Alternate Day Fasting.  Those studies are currently considered the best scientific authority on Intermittent Fasting, and her previous research findings have often been extensively quoted by the majority of Intermittent Fasting Gurus, including Dr. Jason Fung, author of The Obesity Code (2016) and The Complete Guide to Fasting (2016)

Below is a recent article from TIME. 
 

Fasting Isn’t Better for You Than Regular Dieting
Alexandra Sifferlin   May 01, 2017    TIME

Losing weight is hard, which is why weight loss experts have long searched for different approaches to make it easier for people. One strategy gaining steam is intermittent fasting, where people fast or lower their calories substantially for a short period of time. (This diet plan also has potential lifespan-extending benefits.)

But new research published in JAMA Internal Medicine suggests that the fasting diet may not be the weight loss key it's been hyped up to be.

In the new trial, researchers wanted to know whether people who tried a fasting diet would be more successful than those on a standard diet. They told 100 people with obesity to follow one of three diets for a year. Some were told to cut their calorie consumption by 25% per day—a typical calorie restriction diet—while others did an alternate-day fasting diet, where they ate about 500 calories on “fast” days and whatever they wanted on “feast" days. The last group, which served as the control group, ate what they normally would.

The researchers expected that the people in the fasting group would lose more weight and have an easier time sticking to the diet than regular dieters, but the results didn't reflect that. At the end of the year, people who did the fasting diet and those who just cut calories both lost an average of 13 pounds. However, people in the fasting group actually had a harder time sticking to the diet, and more people in that group dropped out of the study.

“I really thought people would have an easier time and lose more weight on the [intermittent fasting diet] and I was shocked they lost the same amount,” says study author Dr. Krista Varady, an associate professor of nutrition the University of Illinois at Chicago and author of the book The Every-Other-Day Diet. “Th...