Dieting Dangers: Navigating the Path to Malnutrition
We often think of dieting as a good thing—eat less, be healthier, right? In reality, cutting calories lower than what we need leads to malnutrition. Along with that much-desired fat loss, malnutrition can cause numerous deficiencies and muscle loss. Each macronutrient, vitamin, and mineral has essential roles in our bodies, and by dieting, we can almost guarantee that we will not get adequate amounts of these nutrients, meaning some of these critical jobs will not get done.
It's unfortunate that in our society, a mildly to moderately malnourished body is equated with health and attractiveness. Even worse, it's often seen as a sign of personal strength and power. We get validated for eating less and moving more. A certain amount of subcutaneous fat loss and muscle wasting is deemed visually appealing and misinterpreted as being fit, whereas a body with an adequate layer of subcutaneous fat is misinterpreted as "fat" and in need of change.
Dieting tells us that we should be fine on 1200 or 1500 kcal, or sometimes even less. But what do our bodies really need to function well and burn the food we consume? Let's demystify the topic of energy requirements. Many of you have heard of these acronyms: BMR, RMR, BEE, REE, AF, TEF, etc. But what do these terms actually mean?
Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR) are often used interchangeably. Though very similar, they have some subtle differences.
Basal Metabolic Rate (BMR) or Basal Energy Expenditure (BEE) represents the energy expended by the body at rest to maintain basic physiological functions such as breathing, circulation, and cell production—in other words, what's needed to survive! It accounts for the largest portion of total energy expenditure (typically 60-75%). BMR does not include energy for voluntary muscle contraction or digestion, absorption, and transportation of nutrients, which all burn even more calories!
Resting Metabolic Rate (RMR) or Resting Energy Expenditure (REE) reflects the energy expended at rest but is measured under less stringent conditions. RMR considers a person's recent food intake and physical activity levels, measuring the number of calories that your body burns while at rest.
TEF or the thermic effect of food represents the energy expenditure associated with the digestion, absorption, and metabolism of nutrients from the foods we consume. In other words, eating itself burns calories! For example, as much as 35% of the calories from certain macronutrients are burned just by digestion and absorption of these nutrients.
Though we are not encouraging calorie counting or fixating on cut-offs in terms of intake, sometimes understanding our energy needs is helpful (and surprising!). One way of doing this is taking your BMR from the Harris-Benedict or Mifflin St. Joer equation and then multiplying it by an activity factor.
Activity factor (AF) or physical activity does not only include exercise but also the energy expended during any form of physical activity, such as exercise, sports, or daily activities like walking and household chores. Physical activity is a variable component that can significantly impact total energy expenditure.
Here is a simple breakdown of activity factors and how they impact total energy needs:
Sedentary: If you get minimal or no exercise, multiply your BMR by 1.2
Examples: Desk jobs, minimal movement during the day.
Lightly active: If you exercise lightly one to three days a week, multiply your BMR by 1.375
Examples: Casual walking, light gardening, easy stretching or restorative yoga sessions.
Moderately active: If you exercise moderately three to five days a week, multiply your BMR by 1.55
Examples: Brisk walking at around 3.0 mph, playing sports like doubles tennis or softball, cycling at around 10-12 mph
Very active: If you engage in hard exercise six to seven days a week, multiply your BMR by 1.725
Running, high-intensity interval training (HIIT), singles tennis, intense weight lifting
Extra active: If you engage in very hard exercise six to seven days a week or have a physical job, multiply your BMR by 1.9
Examples: Professional athletes, labor-intensive jobs like construction or farm work, multiple daily training sessions
Taking all of this into account, a college student who walks to classes, for example, is likely moderately active even without additional "exercise." Once gym time is added, they are likely approaching the very active category. This can easily bump calories well into the 2500-3000 kcal range.
General Signs and Symptoms of Malnutrition
Fatigue: Constant tiredness and lack of energy.
Weakness: General muscle weakness or reduced muscle mass.
Poor concentration: Difficulty focusing or maintaining attention.
Irritability: Increased mood swings or irritability.
Weight loss: Unintentional loss of weight can indicate malnutrition.
Slowed Metabolism: conservation of energy to survive, making weight regain almost inevitable.
Binge Eating: there is much data on how restriction leads to binge eating including the Minnesota Starvation Experiment.
Physical Signs
Dry, scaly skin: Skin may appear dry, flaky, or scaly.
Hair loss: Thinning hair or increased hair shedding.
Brittle nails: Nails may become weak, brittle, or develop ridges.
Dental problems: Increased susceptibility to cavities and gum disease.
Swollen and bleeding gums: Indicates a deficiency in vitamin C (scurvy).
Poor wound healing: Wounds take longer to heal and may become easily infected.
Edema: Swelling, particularly in the legs and feet, due to fluid retention.
Gastrointestinal Symptoms
Loss of appetite: Reduced desire to eat.
Diarrhea: Frequent, loose, or watery stools.
Constipation: Difficulty passing stools.
Bloating and gas: Abdominal discomfort and bloating.
Early Satiety: slowed gastric emptying and premature fullness
Cognitive and Emotional Symptoms
Depression: Low mood, lack of interest in activities.
Anxiety: Increased feelings of anxiety or stress.
Food “Noise”: increased cravings and obsessive thoughts about eating.
Cognitive decline: Memory problems, confusion, or cognitive impairment.
Specific Nutrient Deficiencies
Protein deficiency (Kwashiorkor): Swelling (edema), enlarged liver, and loss of muscle mass.
Calorie deficiency (Marasmus): Severe weight loss, muscle wasting, and stunted growth in children.
Iron deficiency (Anemia): Pale skin, fatigue, shortness of breath, and dizziness.
Vitamin A deficiency: Night blindness, dry eyes, and increased risk of infections.
Vitamin B12 deficiency: Numbness or tingling in hands and feet, balance problems, and memory issues.
Vitamin D deficiency: Bone pain, muscle weakness, and increased risk of fractures.
Calcium deficiency: Muscle cramps, spasms, and osteoporosis.
Iodine deficiency: Goiter (enlarged thyroid gland) and developmental issues in children.
Behavioral Symptoms in Children
Growth delays: Slower than expected growth in height and weight.
Developmental delays: Slower development of motor skills, language, and social skills.
Frequent infections: Increased susceptibility to infections due to weakened immune system.
Poor school performance: Difficulty concentrating and learning in school.
Maybe weightloss diets should come with a black box warning listing all the potential side effects related to malnutrition. Would this make us think twice before cutting our calories so low that our needs are not met? If we were to stop focusing on body weight and fatness as measures of health and worth, would we be less likely to engage in these behaviors? Would we have fewer eating disorders? We encourage you to reflect on these questions and take a stand against diet culture. Aim instead to nourish yourself wisely and with intuition. You may reference this blog on how to cover your nutritional needs or if you prefer the guidance of a diet, consider the Mediterranean lifestyle.
You deserve the compassion that comes from self-nourishment. If you need guidance with this, connect with an ED-informed dietitian.
Blog written by Marlena Tanner, RDN, CEDS-C
The Mediterranean Diet and Minnesota Starvation Experiment documents created by Makenna Kemp, Dietetic Intern