What Happens if I Start Eating Fewer Calories?

Eating fewer calories is one of the basic steps to losing weight, but there are other physical changes your body can go through when cutting down your food intake.  Most of these changes are beneficial, but if you cut calories too low it could have negative side effects.  Here are some changes that happen to your body when eating fewer calories.

Metabolism Slows

Our bodies will naturally increase metabolism after a large meal or during increased calorie intake in general.  When food intake is cut, metabolism can slow.  By eating fewer calories, your body expends less energy breaking down the smaller amount of food.

The amount of calories spent by the body to break down food during digestion is called thermic effect of food (TEF).  It plays a small role in the amount of energy your body uses, but cutting down your food intake will lower the TEF burn.

Basal metabolism could be affected by eating fewer calories.  If calorie intake gets below the amount of energy your body needs to function, metabolic rate could slow to preserve energy.

One of the ways to counteract a lower calorie burn from eating fewer calories to exercise or increase physical movement.  However, if food intake is very low, exercise could be negatively impacted.  You may not have enough energy to physically move more.

Also read: How to fix your metabolism after yo-yo dieting

Weight Loss and Maintenance

One of the first things you will notice when eating fewer calories is that you will probably lose weight.  When calorie intake is less than calorie burn, you will lose weight from fat and carbohydrate stores in the body.

Eating fewer calories can also help you avoid gaining weight.  A 2010 review article from Nutrition Reviews concluded that lowering calorie intake is more effective to avoid weight gain compared to just increasing physical activity.

Increase Mortality

Calorie restriction has been shown in research studies in animals and humans to increase longevity and decrease risk for chronic diseases.  Researchers are not clear for the reason between calorie restriction and health benefits, but some guesses are due to the decreased fat mass, altered insulin signaling or reduced radical damage to body cells.

In most studies, calorie restriction is defined as eating 85% of your energy needs.  Some research suggests the reason Okinawans have such a long life span is because they practice calorie restriction.

Okinawans also have a lower than normal rate for heart disease, obesity and type 2 diabetes which may be from a combination of calorie restriction and quality of their diet.  Okinawans’ diet consist of a majority of leafy greens, root vegetables, soy and small amounts of fish and meat.  The combination of calorie restriction with a diet high in nutrients like antioxidants may offer protection against chronic diseases and improve longevity.

Any increase in longevity from calorie restriction is questioned by some researchers.  The argument is humans are already so close to their maximum life span, calorie restriction would only benefit very slightly for any benefit with mortality.

Improved Mitochondria

Eating fewer calories can cause less damage from oxidation in the body compared over eating.  Researchers from a 2007 article in PLOS Medicine concluded that restricting calories can improve mitochondrial function.  Mitochondria is the power house of the cell, meaning a cell’s metabolism happens in the mitochondria.  Improved mitochondrial function means your body can burn energy more efficiently and with less damage to the cells.

Researchers found decreased body oxidation and damage to DNA in non-obese research participants who followed a calorie restricted diet for 6 months.  More research needs to be done to determine if calorie restriction beyond 6 months has benefit to mitochondrial function.

Easy ways to eat fewer calories

Here are some easy targets for ways to cut calories from your diet.  Focus on cutting out foods or beverages that are empty calories, meaning they only provide calories with little nutrition value.  If you are unsure how many calories to cut out for health or weight reasons, talk with a health professional.

• Cut out sweetened beverages.  Extra sugar in general should be avoided.  Gradually replace sweetened beverages with water or unsweetened tea as much as possible.
• Skip the second helping.  At meal times, fill your plate and skip going back for seconds.
• Load up on fruits and vegetables.  Fruits and vegetables are low energy dense foods, meaning for their volume they provide few calories.
• Cut off extra fat around meat.
• Watch intake of refined grains like baked goods, white bread/pasta/rice.  Replace with smaller serving of whole grains for lowered calorie content, higher fiber and nutrients.

When eating fewer calories you may experience weight loss, improved mitochondrial function, increased mortality or slowed metabolism.  Of course all of these depend on the length and severity of cutting back calories you do.  Quality of calories is still important to remember, especially for health benefits of decreased risk for some chronic diseases and possibly increased life span.

References used in this article