10/18/2013 12:54 pm ET Updated Dec 18, 2013

David Greenwalt: The 4 Fallacies of Undereating -- and How to Overcome This Negative Thinking

By David Greenwalt

If you believe undereating is the solution to fat loss or that undereating is the cause of your weight stall, you may have fallen victim to the fallacies of the underfed metabolism. As a fitness and lifestyle coach, I routinely advise clients who believe undereating is either the answer to, or cause of, their sticking point how to break through weight-loss plateaus. As part of this process, I offer the top four myths and their corresponding truths surrounding an underfed metabolism.

Myth 1: I'm dieting and my metabolic rate slowed down. I've done something wrong!

Everyone knows that to lose weight you must become hypocaloric -- that is, you must consume fewer calories in a day than your body needs to maintain. The hypocaloric state could be thought of as a form of "undereating." You are eating under what you need to maintain. Not only is there nothing wrong with this. It's necessary to strip the unwanted fat.

What many people don't realize, however, is every single hypocaloric person sees a 10-25 percent drop in resting metabolic rate (RMR), the amount of energy expended daily at rest. The fact your metabolism has slowed doesn't necessarily mean you've screwed up your dietary needs. A slower RMR is a naturally occurring response by the body to "protect you" from losing any precious, stored fat -- at least that's how it thinks.

Myth 2: My weight won't budge. I must have stopped or killed my metabolism from undereating.

Your RMR is responsible for 70 percent of all the calories your body burns in a day regardless of how much or how little you eat. These are calories burned, by definition, when you are literally doing nothing -- totally at rest. The only time your metabolism is stopped or killed is when you are dead. In a hypocaloric state your RMR clicks along, 10-25 percent slower than when you are maintaining, no matter how little you exercise or how little you eat. Undereating is not the cause of your weight stall.

Myth 3: I can never consume fewer than 1,200 calories or my body will go into starvation mode and weight loss will stop.

Your body goes into "starvation" mode the minute you cut calories to lose weight. Sure, there are graduations of "starvation" in that cutting 100 calories out of your typical daily diet won't usually create as severe a metabolic slowdown as cutting 1,000 calories but, by enlarge, as soon as you achieve the hypocaloric state you're going to be working with a depressed RMR that has slowed between 10 and 25 percent from normal.

There is no health-robbing, weight-stalling boogey man who lives in the land you can only see when you consume even one calorie fewer than the almighty 1,200, a line-in-the-sand, must-never-ever-go-less-than demarcation that is so prevalently supported in dietetic circles.

Is there a point where eating too few calories can be harmful to health? Sure. Very-low-calorie diets (VLCD) are those where participants consistently eat fewer than 800 calories per day for weeks or months. VLCDs should only be sustained by those under the care of a physician so that proper monitoring of health can be ensured. VLCDs are not the cause, however, of weight stalls. And they most assuredly haven't stopped or killed any metabolisms.

Myth 4: I'm eating 1,000 calories per day and not losing any weight. I need to eat less.

You don't need to eat less. You probably need to eat more -- volume that is. Foods such as leafy greens and fibrous, watery vegetables provide a lot of bulk and volume. High-water, high-volume foods, especially when combined with lean proteins and a little bit of healthy fat are usually the most nutritious and best for maximizing satiety (feeling satisfied or full after eating).

You don't need to eat less. You probably need to eat real food. I define real food as those foods that are old (existed for thousands of years), that are simple, and that are usually a single ingredient. Examples include fresh fruits and vegetables along with beef, poultry, pork and fish without additives or preservatives. Exceptions may include what I call "grandmother multiples." Grandmother multiples are packaged foods that only contain ingredients you would have found in your great grandmother's kitchen, such as tuna packed in water (ingredients: tuna, water, salt) or spaghetti sauce (ingredients: water, tomato paste, diced tomatoes, onions, sugar, salt, garlic powder, spices, basil).

You may need to eat less, but first you need to properly record what you are eating for real. What happens to most people is they don't accurately record what they really eat and their memory serves up the last chicken-breast salad they ate as their standard while conveniently leaving out the handfuls of cereal, bites from the kids' plates at breakfast, the half-cup of intended rice that ended up being a full cup, and so on. You can't legitimately claim you are eating 1000 calories per day if you're not meticulously recording what you eat, if you're eyeballing your measures, or if you're using the trendy palm and fist method of portion control.

If you're overweight and your weight is stuck it's not because you are undereating and you haven't killed or damaged your metabolism. The average woman eating 1,200 calories of real food per day and the average man eating 1,500 calories of real food per day will achieve a healthy weight unless a metabolic condition such as hypothyroidism (underactive thyroid) exists. Very rarely is obesity caused by an underlying medical condition. If you believe you have one I recommend you consult with your physician for testing.

Overeating is a much more serious problem than undereating, particularly in developed nations. Get detailed with food measuring and recording as you strive to understand why your weight may be misbehaving. Contrary to popular, widespread misinformation, you haven't killed or harmed your metabolism even if you've undereaten. Your metabolism is resilient and so are you.

David Greenwalt is the author of The Leanness Lifestyle, a complete body-transformation resource for women and men sick of dieting and ready to permanently lose weight. A certified Wellness Coach, David founded Leanness Lifestyle University (LLU), an evidence-based, lifestyle-education platform that provides users with innovative tools to track, report, and score the behaviors optimal for successful weight-management. To learn more about David and to read his blog, visit him at

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