Weight Gain
Find a nutritionist dealing with Weight Gain »
The term 'underweight' is usually used to describe an individual who is not within a healthy weight range and has less body fat than is required for maximum well-being.
On This Page
Overview
Body fat is estimated using a measurement known as Body Mass Index (BMI), which classifies a person as underweight if their BMI is below 18.5.
Whilst there are some people who have a naturally slender body type, those who are underweight as a result of poor nutrition or a health issue stand a significant risk of developing certain health problems such as anaemia, heart rhythm irregularities, infertility, thinning bones, tiredness, vitamin deficiencies, weakened immune system function and psychological issues among other health concerns.
If you are underweight then gradually and safely gaining weight until you are within a healthy range for your age and height will help to reduce any health risks. If you are considering weight gain then visit your GP or practice nurse beforehand so that they can rule out any underlying medical causes for low weight as well as providing you with some useful advice.
Am I underweight?
Though scales are a useful tool in helping you to track your weight, most household sets are not sophisticated enough to determine if the fat percentage in your body is appropriate for your height. If you are concerned that you are underweight then the best way to measure this is to calculate your BMI.
NHS guidelines currently state that anything between 18.5 and 25 is a healthy weight, and anything above or below poses significant health risks. These guidelines have been developed for use with adults only, with separate charts available for children. It is also worth noting that these markers could be inaccurate for those who have a high muscle percentage, for women who are pregnant or breastfeeding, or for people who are frail.
If you have a set of scales and know your height then you can use the following formula to work out your BMI:
Work out your BMI
- Firstly, find your weight in kilograms and your height in metres. E.g. weight =50 kg height = 1.8
- Multiply your height by itself. E.g. 1.8 x 1.8 = 3.24
- Divide your weight by that figure. E.g. 50 ÷ 3.24 = 15.4
- 15.4 is the BMI which is below the healthy bodyweight range.
If you don't feel comfortable working out your BMI using the formula then there are plenty of BMI calculators online which will do this for you. Alternatively, if you do not have access to a set of scales at home then simply visit your GP or practice nurse, either of whom will measure your height, weigh you and tell you your BMI.
Is my weight already affecting my health?
If you do determine that you are underweight then as mentioned previously, pay a visit to your GP so they can ensure your low weight is not caused by any underlying medical conditions.
At this point your GP may also ask you questions about your energy levels, your menstrual cycle if you are a women and any other aspects of your health which can be visibly affected by low weight. Tests may also be needed to determine the presence of other associated health risks such as nutritional deficiencies, anaemia, type 1 diabetes, osteoporosis or heart irregularities.
In addition to the physical issues which may be caused by low weight, some individuals may also be affected on a psychological level. Our self-image plays an important part in both our confidence and self-esteem and feeling unhappy with weight and image can lead to the development of a mental health concern. By the same token, individuals who are living with a mental health concern such as depression may experience a loss of appetite which has led to sudden weight-loss. In order to determine whether or not there are any signs of a mental health concern, your GP may ask you questions about your current moods, feelings, relationships, work stress etc so that appropriate treatment can be sought.
If it is found that you are underweight because your diet is not providing you with enough calories, then this is something that can be rectified by adopting a healthy and balanced diet.
Risks of being underweight
If you are underweight then you are at a significant risk of developing a range of weight related conditions including the following:
Anaemia
Iron deficiency anaemia is caused by a lack of red blood cells because the body does not have enough iron to produce them. This makes it very difficult for your body to carry oxygen, usually resulting in tiredness and fatigue.
Heart Irregularities
If a person is not taking in enough calories and is underweight, their body will begin to conserve energy by adjusting its normal process and slowing the heart beat. A slower heart beat can cause the blood pressure to lower, which over a prolonged period of time can damage the heart.
Infertility
Women who are underweight may have irregular periods or may stop regular menstruation altogether. When menstruation ceases this is known as amenorrhea, which is a sign that the body's calorie intake is not high enough to maintain optimum function.
Osteoporosis
Osteoporosis is a condition which causes bones to become weak, brittle and more likely to break. Underweight people who do not consume enough bone strengthening nutrients such as calcium and vitamin D will be more susceptible osteoporosis. Woman who stop menstruating as a result of low weight will also stand a higher risk of developing osteoporosis.
What are the causes of being underweight?
A persons bodyweight is determined by the amount of calories consumed in relation to the amount of energy used by the body. If we eat the right amount of calories this means consumption and energy use will be balanced and our weight will remain the same. In contrast, if we consume too many calories the body will take any extra and store them as fat (resulting in weight gain), and if we consume too little, the body will have to dip into its own stores in order to obtain the energy it needs (resulting in weight loss).
However, though these general rules are useful for keeping in mind there are also additional factors which need to be taken into consideration when it comes to determining why someone is underweight, including the following:
Elderly difficulties
Elderly people are at a high risk of malnutrition and being below the recommended weight due to the challenges they face when trying to keep up a healthy diet. Mobility is a huge issue for many as they are unable to move around easily to prepare meals and shop for groceries. Transportation is an additional issue as many individuals do not drive and struggle on public transport. Eating is a very social activity and some elderly people dislike lone eating and will not put effort into cooking for one.
Emotional Issues
A change in appetite may be an indicator of stress, anxiety, depression or other strong emotions you may be experiencing. If you feel consistently worried about eating food or are controlling your eating as a way of helping you to cope with low self-esteem then you may have an eating disorder and should visit your GP who will be able to provide you with appropriate diagnosis, advice and support.
Loss of taste
Eating food is a sensual experience which involves sight, smell and taste, meaning that if one of these senses is impaired this tends to interfere with our appetite. As we grow older our taste naturally diminishes over time, perhaps part explaining why so many elderly individuals lose their appetite.
Malabsorption
Some individuals may be affected by their body's inability to absorb food and its nutrients properly. This may be due to medical or digestive issues such as intestinal damage from an infection or intolerance to a certain protein within some foods. This can result in weight loss, nutritional deficiencies, abdominal pain and various other side effects such as bloating and diarrhoea.
Malnutrition
Malnutrition occurs when a person has an inadequate diet and the body is not receiving enough nutrients, vitamins and minerals to keep their body healthy. It can be caused by not eating enough food, a medical condition or problems with digestion or absorption. In mild cases of malnutrition such as where only a single nutrient is missing, symptoms may be mild or absent. However, severe cases may cause permanent damage to the body.
Overtraining
Though physical activity is essential for staying fit and healthy, sports men and women who spend vast amounts of time working out may burn more calories than they actually consume, leading to low weight.
Underlying illness
Illnesses such as an overactive thyroid, inflammatory bowel disease and coeliac disease may cause a loss of appetite, as may terminal illnesses and their treatment/medication. For example, cancers of the mouth, throat and oesophagus can cause a loss of appetite in the early stages with some sufferers reporting alterations in taste and a difficulty eating. Cancer treatments such as radiation therapy and chemotherapy can also result in nausea and a loss of appetite.
Treatment options
How to gain weight safely
If you are underweight and wish to reduce your health risks and reach a healthier weight range then it is important this is done gradually and safely. It goes without saying that you need to increase the number of calories consumed, but this does not mean eating calorific junk food and zero physical activity.
If you are intending to gain weight then it is advisable you consult your GP or practice nurse before beginning. They will be able to record your current weight, advise you on whether they consider it necessary and provide you with advice about healthy eating and changes to your diet.
Though some individuals may feel confident enough to undergo the weight gain process independently, others will be unsure of how to put on weight and may be concerned it could lead to excess calorie consumption eventually leading to them becoming overweight. Others will simply feel more comfortable with the guidance of a qualified professional and this is something a nutritionist can provide.
How can a nutritionist help me?
A qualified nutritionist will try to help you gain weight safely, and once you have reached your goal will help you to ensure you eat the right amount of food to meet your needs but also to be in balance and remain within a healthy weight range.
Prior to your first consultation your nutritionist may ask you to compile a food diary to help them establish your eating habits. This will allow them to build a picture of what you eat, when you eat and how much you eat. They may also ask you to include other details such as whether you feel stressed or anxious etc as this may help to establish moods which trigger a loss of appetite.
Your nutritionist may also want to carry out certain tests where appropriate to rule out any underlying conditions or to find specific vitamin deficiencies. After a detailed history has been taken, your nutritionist can then move onto formulating a weight gain diet/programme which is specifically tailored to you and your target.
When putting together your programme a nutritionist may take into consideration some or all of the following points:
Physical activity: Eating more calories than you burn is essential for weight gain but ceasing physical activity is not the answer. Remaining active is essential for the maintenance of optimal well-being and many nutrition programmes will include exercise regimes or physical activity recommendations. Be sure to discuss with your nutritionist what kind of exercise your enjoy, or notify them if there are certain activities you are unable to participate in for health reasons.
Food enjoyment: If you do decide to consult a nutritionist then they will provide you with a programme with the intention of you learning to adopt a healthier way of eating indefinitely. The initial adjustment to a different way of eating may be difficult at first but it is important that the foods included on the list are ones that you enjoy and could commit to eating regularly. If there some suggestions you really dislike then its unlikely you will stick to the plan so talk to your nutritionist and see if there are any suitable substitutes or choices.
Your final programme should be achievable and realistic and may include suggested supplements, physical activity recommendations, meal plans and a list of suitable foods.
Regular consultations to monitor your progress will also provide opportunities to seek advice, support and motivation to ensure that you do not stray from your programme and continue to improve your diet and fitness.
An issue which commonly crops up in 'fad' dieting is individuals reaching their target weight, resuming old eating habits and seeing the weight return. In a similar fashion, if an underweight person reaches a healthy weight and then begins to eat as they did before they may experience weight loss once again. In order to avoid this your nutritionist will work with you throughout to ensure any changes made can be integrated into your daily lifestyle and are permanent.
Once you have achieved your target weight your nutritionist may suggest continuing with regular consultations until you feel confident and comfortable with continuing your new lifestyle and weight management independently.
--All content displayed on Nutritionist Resource is provided for general information purposes only, and should not be treated as a substitute for advice given by your GP or any other healthcare professional. Whilst some people have benefited from nutritional therapy, no claims can be made to treat, cure or heal specific conditions, and we strongly advise individuals with any health problem to seek independent medical advice from their GP before considering nutritional therapy.