If you search anything related to “weight loss” or “how to lose weight” almost every source you find will recommend that you reduce your normal calorie intake by 500 calories. That’s because in a vacuum, where everything is black and white and what looks “good” on paper manifests in real life, 3,500 calories is equivalent to one pound of fat. So, if you create a 3,500-calorie deficit each week – 500-calorie deficit each day – you can expect to lose one pound – of fat – per week.

If only weight loss was that simple…

You and I both know there are about 1,000 moving parts when it comes to trying to lose weight and keep it off. If losing weight was truly as easy as reducing your normal intake by 500 calories, well, let’s just say the current obesity epidemic, which continues to get worse, by the way, would never have occurred.

What’s often overlooked about this recommendation, however, is not that there is much more to weight loss and maintenance than one simple calorie reduction, but that in some instances, this recommendation does more harm than good.

Allow me to explain…

ESTIMATED CALORIE NEEDS

Jessica is a 31-year- old woman who’s looking to lose a little weight to feel more comfortable in her bikini this summer. She’s five feet and three inches tall and weighs 138 pounds. Assuming she has no major dieting history, has not dieted in the past six months, and has an average amount of muscle mass for someone her age, height, and weight, we can use the Mifflin St. Jeor Equation to estimate that Jessica needs 1,310 calories per day to survive (her Basal Metabolic Rate). Now, if we also assume she attends four to five CrossFit classes each week, we can estimate her activity level at 1.4.

1,310 X 1.4 = 1,834 calories – the (estimated) number Jessica needs to maintain her weight based on her age, height, weight, gender, and exercise habits.

Note: The Mifflin St. Jeor Equation is an approach to estimating one’s resting energy expenditure and used to derive and estimated basal metabolic rate, too. Your basal metabolic rate equates to the number of calories your body needs each day to carry out functions essential to survival, e.g., breathing, blood circulation, organ support, etc.

Activity factor is a number – typically between 1.0 and 2.0 – that is used to best characterize the number of calories you burn per day via activities of daily living, your job demands, and exercise habits. This number is multiplied by your resting energy expenditure (derived from the Mifflin St. Jeor Equation) to arrive at a number that estimates the number of calories needed to maintain your weight.

THE 500-CALORIE DEFICIT EFFECT

After a quick Google search about dieting, and finding out that she needs roughly 1,834 calories per day to maintain her weight, she decides to commit to tracking her food daily and to aim for 1,334 calories per day – 500 less than her estimated maintenance amount.

At first, this is wonderful. The weight is practically melting off. But within a few of weeks, weight loss begins to stall. And for another week she seems to be stuck at 132 pounds. Deciding it’s time to make a change, Jessica reduces her calorie goal again….by another 500 calories.

This brings her daily goal to 834 calories…

As you can imagine, hunger and fatigue set in almost instantaneously. She’s ravenous and irritable, and knows this isn’t sustainable. “But I’ll look so good in my bikini,” she tells herself. Just 10 days into this second phase, Jessica caves. She eats an entire large pizza and spends a lot of time with Ben and Jerry later that night. When she finally musters up the courage to look at herself in her new bikini, she’s horrified. It’s as if she’s taken five steps backward. And when she steps on the scale, well, that’s not any more forgiving, as it reads 137 pounds – one pound away from her pre-diet weight.

“But I reduced my daily calorie intake by 500 calories just like every internet source told me to!” she exclaims.

WHY DID THIS OCCUR?

When you reduced your daily calorie intake, your body fights back because it views this deficit as a threat to survival. In an effort to conserve energy, your body reduces total daily energy expenditure (TDEE) through a variety of channels. Your metabolic rate, which makes up roughly 70 percent of your TDEE, takes the biggest hit and has a large impact on the total number of calories you burn per day. This is because it’s highly dynamic, which means it adapts quite quickly to any significant change in calorie intake. In short time, that 1,334 daily calorie goal, which was once a 500-calorie deficit, becomes a new maintenance number and ultimately, weight loss stalls. This is what Jessica experienced when she was stuck at 132 pounds.

To further drive weight loss when you experience a plateau, you must again reduce calories, increase exercise, or a combination of both to recreate a calorie deficit. This is why Jessica reduced her calorie goal by another 500 calories.

The problem with this “500-calorie” rule, however, is that 500 calories is a different percentage of total calories for everyone. For Jessica, an active 31-year- old female, 500 calories represented 27 percent of her baseline calorie intake. And then 37 percent of her new baseline phase. For a larger individual, for instance, someone who is maintaining their weight on 2,500 calories per

day, this 500-calorie amount is only a 20% deficit.

In Jessica’s situation, this 500 number was inappropriate. It was too large of a deficit, which is why she immediately found herself in a tough spot, consuming very few calories and battling frequent hunger and fatigue. It was a recipe for failure right from the beginning.

Had she chosen a smaller deficit, she would have set herself up with a much more sustainable approach, and one that would’ve likely yielded better end results because she would’ve had a much easier time sticking with her diet to the end.

HOW MANY CALORIES SHOULD I REDUCE WHEN SEEKING WEIGHT LOSS?

I recommend that you begin with a 10 – 15 percent calorie reduction. This number of calories will be enough to start weight loss, but also put you in a position to have plenty of calories to work with as you move forward.

CALORIE GOAL

10%

15%

1500

150

225

1600

160

240

1700

170

255

1800

180

270

1900

190

285

2000

200

300

2100

210

315

2200

220

330

2300

230

345

2400

240

360

2500

250

375

2600

260

390

2700

270

405

2800

280

420

2900

290

435

3000

300

450

Remember, the goal of any diet should be to lose weight while eating as many calories as possible. If you can lose weight eating 2,000 calories per day, why eat 1,700?

Taking a slightly more conservative approach to weight loss may test your patience, but it may also be the differentiator that allows you to stick with your diet for the appropriate amount of time to reach your goals AND be the reason you do no give into binge-like behaviors as you transition into a post-dieting maintenance phase.