Will Eating 1,000 Calories a Day Cause Weight Loss?

Effects of Reducing Calories to 1,000 per Day

Whichever method you use, consuming only 1,000 calories per day presents several health risks.

Malnutrition

One of the risks of eating fewer calories is missing out on the protein, fat, carbohydrates, vitamins, and minerals that accompany those calories. If your body doesn’t get nutrients in the amounts it needs to function, malnutrition can occur.

“The standard 2,000-calories-per-day diet that lines up with U.S. Food and Drug Administration recommendations essentially provides the general recommended nutrient needs,” says Sarah Koszyk, RDN, a registered dietitian-nutritionist in San Francisco.

If you’re cutting that diet in half, your micronutrient intake will likely be cut in half, too. “A low-calorie diet can result in vitamin A, B, C, D, E, and K deficiencies, in addition to minerals like calcium, magnesium, iron, potassium, and zinc,” Koszyk says.

• Bone and muscle loss
• Weakness
• Fatigue
• Hair loss
• Low heart rate and blood pressure
• Frequent infections

“Your body can shut down over time if it’s not getting the nutrients it needs to sustain itself,” Koszyk adds.

Slower Metabolism

Following an LCD or VLCD can lead to dramatic weight loss — at least in the beginning.

But the rapid weight loss often seen with a 1,000-calorie diet can slow your resting metabolic rate, or how many calories you burn at rest. This can contribute to weight regain and sabotage your weight loss efforts over time.

“When people lose weight, their resting metabolic rate slows down to adjust to the body’s reduced energy needs,” Koszyk says. Eventually, your body stops responding to the calorie deficit.

All of these factors make weight regain more likely after a drastic calorie deficit.

Reduced Mental Edge

Gallstones

Safety During Exercise on a 1,000-Calorie Diet

But if your calorie deficit is already significant, exercising while following a VLCD can be risky unless you’re working with a healthcare professional who can keep tabs on you.

“A common side effect of low-calorie diets is fatigue and low energy,” Koszyk says. Without enough calories to power your workouts, you can get lightheaded, dizzy, or nauseated.

In addition, exercise requires adequate nutrients for recovery. “With a very-low-calorie diet, you may not get the necessary protein and nutrients post-workout, which can result in injury, deficiencies, fatigue, and muscle loss,” Koszyk says.

Consult a healthcare professional before combining an LCD or VLCD with exercise.