Is Chronic Under-eating Getting In The Way of Fat Loss?

Despite the idea that weight loss comes down to a simple “calories in, calories out” formula, a variety of lifestyle factors affect the ways our bodies respond to exercise and food. And while a reasonable caloric deficit over time should cause sustainable weight loss (think a deficit of 300-500 calories per day), much larger caloric deficits over time can create undesirable changes in metabolism in an effort keep the body in an energy balance and maintain homeostasis (the body’s self-regulating system that maintains internal stability and basic functions like regulating breathing, body temperature, and blood pressure)

For many of us chronic under-eating, that is, being in a severe caloric deficit for an extended period of time, is actually getting in the way of fat loss. The body, (which prioritizes survival), it is constantly regulating what's going on in response to our environment. If we are in an extreme caloric deficit the body will direct calories to necessary functions for survival. An extremely low calorie diet looks like 1000-1200 calories per day. If we are in this “survival mode” state, the body is actually burning fewer calories, even as you’re exercising regularly and intensely. This means we may hold onto body fat despite eating a low-calorie diet and training hard.

Undereating can also negatively impact training. When the body feels it must prioritize survival, it isn’t going to put energy toward things like rebuilding muscle tissue, which is the process that enables it to build strength. Exercising becomes harder than it used to, and even though we may feel like we’re performing with all we’ve got, we’re actually training at a major energy disadvantage.

Chronic undereating also raises stress hormones like cortisol. Long-term elevated cortisol leads to insulin resistance, a hormonal state that can lead to stalled weight loss and body fat retention.

Additional negative effects of chronic-under eating:

1.    Slower metabolism and lousy side effects. With too few calories on board to power you through your daily activities, your body learns to live on less by significantly slowing your metabolism. Short term, you may feel sluggish, irritable and apathetic. Once you stop undereating, it takes awhile before your body to recover and your metabolism to rev back up.

2.    Loss of valuable muscles and organs. Just because you’ve adapted to using ketone bodies doesn’t mean your body won’t need glucose at all. A minimum blood glucose level must be maintained to keep you alive so your body continues to break down muscles and organs. It’s a major problem in the long run, because your body doesn’t distinguish between essential tissues (think: heart, kidney, blood cells) and less essential tissues (think: skeletal muscle). Over time, this breakdown weakens and damages your vital organs.

3.    Higher risk for nutrient deficiencies. Eating very few calories will also decrease the variety of foods you can eat, increasing your risk for nutrient deficiency. The type of nutrient deficiency that can occur depends on the food(s) that are being restricted. While not everyone who chronically undereats can automatically be diagnosed with an eating disorder, anorexia gives insight on the types of nutrient deficiencies that are likely to occur from prolonged starvation. This includes but isn’t limited to deficiencies in calcium, iron, zinc, vitamin D and B vitamins, in addition to dangerous electrolyte imbalances and protein malnutrition.

(blog.myfitnesspal.com/why-undereating-wont-actually-help-you-lose-weight/)

So, how many calories should we be eating then? This is a hard question to answer and is going to vary greatly from person to person based on a multitude of factors (activity level, body size, resting metabolic rate, muscle mass and genetics to name a few). It’s also virtually impossible to measure our metabolism, and the tools we do have for measuring are wildy inaccurate.

A very general way to calculate caloric needs if you train 3-5 days per week is to multiply your bodyweight in pounds by 15. For example, 150 lb x 15= 2250 calories per day.

If you are then looking to lose 1 pound of body fat per week, subtract 500 calories from your daily target.

The best way to figure out our caloric needs ignores calculations entirely. If you are reading this, you are most likely aware whether you are losing weight, maintaining weight or gaining weight with your current nutrition. Let this be your guide toward the ideal number of calories for you- it may take some trial and error.

As far as food is concerned, if you’re looking to build muscle and/or lose fat while training regularly, a daily macro percentage goal of 30 percent protein, 40 percent carbs, and 30 percent fat is a good place to start.