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Diet therapy

Are you energy deficient?

Energy deficiency is not just a problem of third world countries.

Living in New Zealand where 34% of New Zealand adults (13% children) were obese and 34% of adults (18% of children) were overweight in 2021 1 it may be hard to imagine that malnutrition could be a health problem.

However energy deficiency can be found in our hospitals, schools and kindergartens, rest homes and on our sports fields. It can affect over and underweight people.

What is energy deficiency?

This comes about when there is a mismatch in the factors responsible for energy balance :

Energy intake (available energy) less Energy expenditure (the cost of exercise) relative to Fat free mass (FFM)

Energy intake

A drop in energy intake can occur:

  • Intentionally such as when food intake is limited in order to lose weight.
    Provided that minimum nutrient requirements are met a safe weight loss of 0.5-0.7kg/week can be achieved until a healthy BMI is reached. At which point weight maintenance guidelines need to be given.
    A Dietitian should be consulted to assist with this process.Problems can arise however if weight loss is not supervised, if weight loss gets out of hand, minimum nutrient standards fail to be met and if weight falls below a BMI of 18.5 2If weight loss is also accompanied by the use of medication such as diet pills, laxatives, diuretics or induced vomiting then professional help should be sort.
  • Unintentionally weight loss > 10% over previous 3-6months  can occur as a result of long-term illness, hospitalization, neglect, mental illness, body trauma etc and needs to be recognised and treated without delay.

Energy expenditure

An increase in energy expenditure can be due to a variety of factors such as:

  • Exercise regimes: over training, increased work load e.g cycling over steep terrain or running over longer distances.
  • Climate: very high and low temperatures, high wind velocity challenge the body’s thermoregulatory systems increasing energy use.
  • Increased demands: due to growth, pregnancy and breast-feeding
  • Increase in metabolic rate: due to such things as trauma, surgery,
  • Increase in respiratory rate: due to lung disease e.g. asthma, COPD, changes in altitude
  • Increase in heart rate: associated with illness such as congestive heart failure, cardiac arrhythmias.

Fat free mass (FFM)

This is all the body’s non-fat tissue e.g. skin, bones, ligaments and tendons, organs and water content. A high level of FFM implies a lean and healthy body however too much FFM can be unhealthy. Adult men and women require around 45kcals/Kg/day to maintain FFM and energy balance.3

Note: Contrary to popular opinion not all fat is bad

  • Essential fat is an energy source and also supports and insulates our organs, nerves and brain tissue. Men require at least 3-5% essential fat to function properly This can be hard for athletes such as body builders or long distance runners to maintain.
    As women have sex specific fat in their breasts, genitals and other areas approximately 12-15% is essential for normal body functioning 4
  • Non -essential fat (adipose tissue) that accumulates through dietary excesses is the most concerning as this type of fat can lead to heart disease, cancer and obesity and requires treatment.

So if energy intake falls or is unable to meet the increased cost of energy expenditure then energy deficiency occurs.

The effects of energy deficiency

As energy intake falls it sets in motion a chain of physiological impairments 3 that over time can endanger health and lead to eating disorders

Physiological impairments Examples of impact on general health
Immunological Failing immunity
Menstrual function Loss of periods, infertility
Bone health Stress fractures, osteoporosis
Endocrine Changes in insulin, growth and appetite hormones
Metabolic Reduced body building, increased body breakdown
Haematological A slowing of blood cell formation
Growth & development Failure to thrive, stunting, delayed motor skills etc
Psychological Mental illness, poor memory, fatigue, depression
Cardiovascular Myocardial muscle declines, also cardiac output
Gastrointestinal Altered digestion & gut motility, bloating, diarrhoea

Groups at risk

A drop in energy balance at peak times of growth, exercise performance, illness or advancing age can greatly impact on physical development, performance, body repair, long-term health and well-being. Let’s see who may be affected most.


  • Weight change in athletes may begin with appropriate healthy eating and sports nutrition advice with weight loss or gain recommendations as necessary. However over time, and if not supervised, energy deficiency can escalate particularly if there is injury or if changes in training load are not matched with specific guidelines regarding food quantities.
  • Other non-dietary factors such as psychological stress caused by such things as financial pressures, equipment failure, poor sleep patterns, can add to the mix and affect appetite as anxiety grows.
  • Sports specific factorssuch as making weight, frequent weight cycling, early morning starts, over training, recurrent and non-healing injuries, inappropriate coaching and the regulations governing some sports can contribute to energy deficiency and the development of eating disorders.3

Relative energy deficiency in sport (RED-S) is a syndrome now used to describe the gradual decline in physiological processes (see table above) that occurs when athletes experience a lack of energy availability (LEA).5

If an athlete’s energy intake is less than their energy output, there is less energy available to fuel bodily functions as well as their exercise or training programme. To continue exercising, on less fuel, the body has to either slow down or stop, its normal body functions.

In the case of female athletes, this process was once described as the female triad syndrome (when female athletes are caught in a triangle of low energy availability, loss of menstruation and low bone density).3 The RED-S model has broadened this concept to recognise other physiological impairments that may affect both male and female athletes when energy deficiency is left unchecked

If left unchecked, the decline in energy and resulting physiological changes may increase the risk of injury and illness. As mental health declines, athletes may become depressed, irritable, lack concentration, judgement and co-ordination. As muscle strength and glycogen stores decline, there is a loss of endurance performance.

It is important to note that not all individuals with LEA will have all of these symptoms occurring, nor appearing in a consistent sequence. Also, there is still a lack of protocols and resources to measure the degree of LEA in sport 6

The important thing for parents, is to be aware that RED-S can happen, and that parents, coaches and team managers need to be alert to the pressures exerted on athletes to perform and the effects that these pressures can have on energy consumption and health.

People who are overweight or obese

Obesity can mask energy and nutrient deficiency 7 because:

  • Vitamins, minerals and dietary fibre essential for good health may be lacking.
  • Some nutrients are essential on a daily basis. So although it may be tempting to believe that an overweight person can skip meals, fad diet and live off their fat for some time this is not so. With this approach the very nutrients needed to assist weight loss may be lacking. Also if applied to overweight children this philosophy could affect their growth, mental and physical development.
  • Fluid retention or oedema due to inflammation, often associated with obesity, can mask loss of muscle tissue and malnutrition

If people of any age are contemplating weight loss professional help should be sort.



Achieving an energy balance throughout childhood can be a juggling act for parents 7

  • Picky feeding habits of young children and food fads can impact on energy intake at a time when a child’s energy and nutrient demands for growth are considerable.
  • Childhood illness can interrupt eating making it difficult to regain appetite and “catch up on “ growth rate.
  • Adolescence meals can become less structured and adequate, as more foods are eaten “on the run” or with friends, than supervised by parents. Some meals may be skipped altogether particularly breakfast and lunch if running late for school or if time is lacking between classes or there are after school activities or sport. This can mean that at a time of peak growth (which for girls is 10-14yrs; boys 12-17yrs) energy intake may be compromised.
  • Sporting commitments can redirect energy away from growth and into physical endurance. All of which can be detrimental to health and performance.
  • Overweight children need special care so parents should avoid applying their weight loss regimes to their children. Instead they need programs that are tailor-made to match their age, energy needs for growth and activity. 8

The Elderly

Energy requirements vary widely according to gender, body size and physical activity but generally decrease with age due to a reduction in basal metabolic rate and muscle mass 9  Low energy intakes can be due to:

  • Functional changes such as ill-fitting dentures, dry mouth syndrome, reduced production of saliva, changes in sensations of taste and smell. Swallowing difficulties can also occur with ageing and reduce overall food consumption.
  • Loss of appetite or interest in food preparation can lead to failing health in the elderly particularly in those who have lost a spouse and/or are living alone.
  • Chronic illness and failing mental health can lead to marked weight loss, malnutrition and declining mobility.
  • Medication can alter energy intake by interfering with nutrient absorption and requirements.

Social interaction can help to maintain good health as sharing meals with family or friends may increase the amount and variety of foods eaten.  However if elderly people are unable to maintain a healthy body weight then professional help should be sort to discuss suitable dietary supplements and care.


Australian and international research has found that malnutrition is a significant problem in hospital patients. Prevalence varies from 25-40% in hospital patients and 5-10% in outpatients 2 Malnutrition not only delays recovery and extends hospital stay but can also necessitate later readmission. In Australia and New Zealand nutritional screening upon hospital admission is now mandatory.

Hospitalization can also contribute to a poor energy balance for reasons such as:

  • Trauma experienced at any age, can lead to rapid weight loss. This can be particularly severe following surgery or injury as energy expenditure increases to maintain vital body systems.
  • Meal times can become interrupted particularly when in hospital by specialist medical rounds, trips to treatments , physiotherapy or x-ray appointments , visitors and periods of ‘nil by mouth’ for surgery. This can make it difficult for patients to meet daily energy and nutrient requirements.
  • Missing favourite foods can lead to loss of interest and declining intake. Although institutions work hard to make food look appealing it can never replace a home cooked meals shared with those you love.

Tips to maintain your own energy balance

  • Be aware of how energy needs change with your age and activity levels
  • Strive to reach a healthy body weight and maintain it throughout life.
  • Respect your body’s need for fresh healthy food each day.
  • Concentrate on developing a meal pattern that is adequate and flexible enough to suit your energy needs for work, sport and exercise
  • Be aware of how your changing environment can impact on your food intake e.g. if travelling away from home ensure food is available.
  • Physical activity has an important role to play in energy balance, it maintains muscle mass and strength, stimulates appetite and maintains social connections, so keep active throughout life.
  • Have regular medical check-ups with your GP and pay attention to oral hygiene.
  • Females, particularly athletes should see any interruption in their menstrual cycle as a problem and seek help.
  • Be aware that feelings of anxiety can affect us at any age and impact on food intake, depressing appetite and increasing sleep disturbance. Be sure to discuss this with your GP if these things affect you.
  • Avoid embarking on strict or fad dietary practices. If you need to lose weight or dietary information then contact me for professional help

For more information here are some more articles by Lea:

Sports nutrition for women

Sports nutrition for Masters athletes

Overcome misconceptions about nutrition for better family health

Feeling full is the secret of weight loss

Care for “the carers” during family illness

Could your weight be disabling you?

Sleep for better self-regulation

How to help athletes to recognise the mental health risk of sport

Dietary help for depressed athletes

Don’t let disordered eating ruin your performance


  1. Obesity & overweight stats in New Zealand 2020-21 
  2. Baker L, Gont B, Crowe T Hospital malnutrition : Prevalence, identification and impact on patients and the health care system. Intern J Environ Res Public Health 2011 8 (2):5154-527.
  3. Mountjoy M, Sundgot-Borgen J, Burke L, Carter S, Constanti N, Lebrun C, Meyer N, Sherman R, Steffan K, Budgett R, Arue L . The IOC consensus statement: beyond the Female Athlete Triad- Relative energy deficiency in sport (RED-S) Brit J Sports Med 2014.48:491-497.
  4. Burke L The complete guide to food for sports performance 1995 ,3, 61
  5. Mountjoy M., Sundgot-Borgen, J.K., Burke, L.M., Ackerman, K.E., Blauwet, C.,Constantini, N., Lebrun, C., Lundy, B., Melin, A.K., Meyer, N.L., Sherman, R.T., Tenforde, A.S., Torstveit, M.K., Budgett, R., ‘IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update’, British Journal of Sports Medicine, 52(11), 687–97.
  1. Burke, L.M., Lundy, B., Fahrenholtz, I.L., Melin, A.K., ‘Pitfalls of conducting and interpreting estimates of energy availability in free-living athletes’, International Journal of Sport Nutrition and Exercise Metabolism, 28(4), 350–63.
  1. Clinical guidelines for weight management in NZ adults MOH 2009
  2. Food and nutrition guidelines for healthy children and young people 2-18: A background paper MOH 2015.
  3. Food and nutrition guidelines for healthy older people: A background paper MOH 2013

About the author View all

Lea Stening

Lea is one of New Zealand’s leading paediatric dietitians and also specialises in Sports Nutrition. She has specialised in Paediatric Nutrition for 31 years and in 1985 was the first paediatric dietitian to enter private practice in New Zealand. Lea helps families through her private consultations, public lectures, newspaper and magazine articles as well as television and radio interviews. Read more »

View all posts by Lea Stening »


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