The Body Mass Index (BMI) is a measure of body fat that is used by the medical profession to determine a person’s weight in regard to the height.

BMI applies to adult men and women and assesses whether people are underweight, of a healthy weight, overweight or clinically obese.

Why does BMI matter?

People who are classed as clinically obese possess a greater risk of developing diabetes, as well as cardiovascular diseases,

cancer
and suffering a

stroke

You can use the BMI tool to tell how healthy your weight is for your height, however, BMI has its drawbacks and arguments have been made against it.

Guide to BMI

Explore BMI; from why it’s important to how to take your waist circumference in order to calculate your BMI.

GUIDE TO BMI

Why is BMI Important?

How to Calculate BMI

Measure Your Waist

Is BMI a true measure of my health?

Body fat is not taken into account when compared to muscle content, so a tall athlete in excellent physical condition may have a higher BMI than someone who is overweight.

BMI is also no indication of general fitness or health, with another criticism aimed at BMI readings that age is not taken into consideration.

BMI (Body Mass Index) is important as it is widely regarded that your chances of having a longer and healthier life are improved if you have a healthy BMI.

If your BMI is high, you may also have an increased risk of developing

type 2 diabetes, as well as other metabolic diseases such as

hypertension, high cholesterol and heart disease.

Relationship of BMI with diabetes

Research shows strong links between a high BMI and type 2 diabetes, with the risk of the condition rising with each increase in BMI.

Data studies

A review of over 12,000 people in the United States, published in 2014, showed that people with a BMI of 25-29.9 had a 50% increased risk of diabetes compared to people with a BMI of 18.5-24.9.

Obesity was linked with increased rates of diabetes between 2.5 and 5 times higher than people of normal weight, with the highest risk being those with a BMI of 40 or more. The results found:

• 
  BMI 25-29.9 (overweight):
  
  50% higher type 2 diabetes risk
• 
  BMI 30-34.9 (obesity class I):
  
  2.5 times more likely to get diabetes
• 
  BMI 35-39.9 (obesity class II):
  
  3.6 times more likely to get diabetes
• 
  BMI 40+ (obesity class III):
  
  5.1 times more likely to develop diabetes

BMI and other long term health risks

The World Health Organisation (WHO) lists a high BMI as a major risk factor for heart disease, stroke, bone and joint problems including osteoarthritis and a number of cancers, including breast, colon and endometrial cancer.

Large scale surveys, such as SHIELD (Study to Help Improve Early evaluation and management of risk factors Leading to Diabetes), conducted in the USA in 2004, show clear associations between a raised BMI and increased risks of hypertension (high blood pressure) and dyslipidaemia (high cholesterol) in addition to type 2 diabetes.

How health care professionals use BMI Formula

BMI is checked regularly by doctors to assess if people are at a healthy weight, with advice dependent on what your BMI reading is:

• 
  Below 18.5 BMI:
  
  advised to eat more to gain weight within a normal range
• 
  Between 18.5-25:
  
  you are of normal weight
• 
  Between 25-30 BMI:
  
  advised to lose weight and exercise more to reduce risk of obesity
• 
  Over 30 BMI:
  
  specific diets and weight loss programmes suggested, as well as referral to a dietitian.

Diet and weight loss programmes

If you have a BMI over 30, you may be referred to join a weight loss group or given exercise on prescription.

Weight loss groups may be commercial slimming groups or those provided by the NHS. Exercise on prescription involves being referred to receive a number of sessions of physical activity with a health team or a qualified trainer.

Your health team should provide you with guidance on changing eating habits and exercising efficiently to achieve the best possible benefits.

Some people may be considered to go on a very low calorie diet of 800kcal per day. This requires medical supervision and may not be advisable in certain groups of people.

Bariatric surgery

In the UK, you may be considered for bariatric surgery in the following cases:

• Having a BMI over 35
• Having a BMI over 30 and having recently been diagnosed with type 2 diabetes

People of Asian origin may be considered for weight loss surgery if they have been diagnosed with type 2 diabetes within lower BMI brackets than 30.

Follow-up appointments will be carried out to ensure your diet, medication and level of support is appropriate to prevent weight being regained.

Certain shopping habits can prove detrimental for some people, and actually play a big part in how easy it can be to put on weight.

Special deals advertised by supermarkets can be tempting when larger products are discounted at a much lower price, regardless of how healthy they are.

This can lead to people buying excess food that they don’t really need and  in greater portions than recommended.

Putting on weight
can be easily done from bad shopping habits, so planning your shopping activity in advance is important to avoid certain supermarket pitfalls.

Eat before shopping

If you haven’t eaten before you shop, it is likely that hunger pangs that strike at the supermarket can lead you to make the odd impulse purchase.

Make sure you have eaten, and you are full before you head out to do your grocery shopping. Feelings of hunger will therefore have less of an influence, which will not only prevent you from buying food that may be unhealthy, but also reduce your shopping bill.

Make a grocery list

Making and sticking to a grocery list is important as it gives you a sense of direction when entering a store.

Knowing exactly what you need to buy can prevent you from getting sidetracked and potentially forgetting to buy important items in favour of unplanned purchases.

A grocery list can also save you time when shopping. By crossing off items as you go along, you can work out which aisles to visit next rather than just walking up each one and seeing what things you could buy.

Buy the right foods

Dedicate your shopping list to buying the foods that are best for you when shopping, including fresh fruit and vegetables and

lean cuts of meat
and

fish

Reduce the amount of sugary foods
in your trolley that will result in additional calorie consumption and try to implement whole grain changes into your diet.

Buy brown bread instead of white to gain the most nutrients, while buying whole grain rice and cereal will also be more beneficial for you than white or sugary counterparts.

Buy and try a new fruit or vegetable

The policy of buying and trying a new fruit or vegetable is one element where not sticking specifically to your grocery list can be beneficial.

The nutrients found in most fruit and vegetables make them worth purchasing, especially if you have not had particular ones that you may be interested in trying.

Try one new piece of fruit or

vegetable
each time you go to the supermarket to liven up your meals or snacks for when you get home.

Adopting a healthy diet will enable you to lower your BMI (Body Mass Index), as simply increasing your level of activity might not be enough to lose weight.

Calorie deficit

Reducing how many calories you eat will assist in your weight loss, as the calories in foods people eat can quickly add up.

Entering a calorie deficit, where you eat fewer calories than you burn in a day will prevent you consuming excess fat that serves to increase your BMI.

Starting to cook for yourself more can help you monitor your food portions and subsequent calorie intake.

Check food labels to be sure you are eating the smallest amount of saturated fat possible, and so you can avoid the fats that come from fried and baked foods.

Change your shopping list

Fruit and vegetables

Adding five servings of fruit and vegetables a day can add nutrition to your diet, which will also serve to fill you up.

Vegetables, especially, are packed with the nutrition our bodies need to feel satisfied and they’re generally low in calories.

Using dressings, herbs and spices can make vegetables more appealing if they do not normally make your shopping list on a regular basis.

Whole grain replacements

High sugar foods such as sweetened cereal, chocolate and pastries should be avoided, as well as sugary soda drinks.

Replace starchy version of foods such as bread, flour and rice with whole grain foods. Whole grain foods are less heavily processed than their white counterparts and contain significantly more fibre and natural nutrition.

Attack snacks

It can be quite tempting to buy snacks when shopping, but snacks such as crisps and chocolate can contain excess calories.
Buy some chewing gum to replace these snacks when hunger strikes, while drinking a large glass of water can also fight off hunger pangs.

Change your diet

Ditch highly processed foods

Processed food should be avoided as part of your diet, with a generally reliable rule being the more processed a choice of food is, the worse it is for your health. Very processed foods tend to include:

• Highly refined carbohydrate – which sharply raise blood sugar levels
• Man made fats
• Added glucose, sugar and salt
• High levels of preservatives
• Very little fibre

Fibre intake

Increasing your fibre intake will not only give you more energy, but it will also help you regulate your body’s systems.

Your

BMR (Basal Metabolic Rate), which is the number of calories required to keep your body functioning at rest, will increase following enhanced fibre. This can also speed up your weight loss in the process.

Whole grain ingredients and products will also assist you in your fibre increase, while whole wheat flour and oatmeal are other good fibre sources.

Make use of protein

Protein has a number of distinct benefits because it provides fewer calories per gram than carbohydrate or fat and keeps you feeling full for long periods of time.

If you need to be strict on calorie content, opt for lean meat such as chicken breast and cuts of red meat with the fat trimmed off.

Eggs are a strong and versatile choice and beans are lentils are a great choice, particularly for people following vegetarian or vegan diets.

Lean meat

Eating lean meat can assist with weight loss as it contains significantly more protein and has less fat and carbohydrate content.

Chicken generally tends to be very lea, with the white of the meat containing less fat than the meat found on the thighs or wings.

Red meats such as beef and pork are also beneficial, with the leanest cuts available containing more beneficial materials such as vitamin B, iron and zinc.

Your BMI may not always be an entirely accurate representation of carrying excess fat, including:

• When pregnant, or having recently given birth, and/or nursing
• Having muscular or athletic build

In these examples body weight and BMI may be higher for reasons other than excess body fat, and therefore BMI would be a less useful indicator of health.

Also, BMI does not distinguish between body fat and muscle mass, which is why muscular athletes may have a high BMI because of increased muscle rather than additional body fat.

Is BMI reliable as an indicator of body fat?

BMI can be useful as a rough guide, and there is a correlation between BMI and body fat, however it is also dependent on sex, race and age.

At the same BMI level, men tend to have less body fat than women, while older people generally have more body fat than younger adults, on average.

Another simple measure to assess body fat and health risk is waist circumference.

Guidelines from the National Heart, Lung and Blood Institute recommended looking at waist circumference – as abdominal fat can lead to obesity-related diseases – and other risk factors associated with

obesity
such as physical inactivity and

high blood pressure

When your BMI is calculated, it will translate to being underweight, in the healthy range, overweight or obese.

Underweight

If your BMI reading is below 18.5 then you would be classed as underweight and advised to eat more to gain weight within a normal range.

Risks of being underweight

You should consult your GP if you need to gain weight, as low body mass can damage your health and decrease your body’s immune system.

When your immune system is not 100 per cent, you are more likely to catch a cold or other infections, as you lack vital nutrients required for your body to grow, fight infections and work properly.

Among the risks that come with being underweight and having a weakened immune system include:

• 
  Loss of periods for women
• Lack of calcium – resulting in failure to maintain strong and healthy bones
• Malnutrition
• Weakened muscles – including your heart

Losing weight without trying

If your BMI reading classes you as underweight, and if you have not being trying to lose weight, you should consult your GP to see if other problems are causing this weight loss.

Emotional issues such as feeling anxious when thinking about food could be stopping you from eating a healthy diet.

Experiencing high levels of stress, or other emotional problems, can result in a change in eating patterns that may be hard to recognise, but could result in you losing weight.

If you are exercising control intentionally to avoid eating food, this could be a sign that you may have an

eating disorder

Alternatively, there may be an underlying medical cause for your low weight, such as an

overactive thyroid

Steps to achieve a normal weight

Adopting a healthy, balanced diet can assist with achieving a normal, healthy weight for your height and age, but it is important to gain weight gradually rather than in a rush.
Increasing weight the right way is crucial.

Avoid foods that increase your body fat rather than your lean body mass such as

chocolate, cakes and other high-calorie foods.

Aiming for three meals and three snacks a day, involving

starchy carbohydrates
– such as pasta, rice or potatoes – as well as fruit and vegetables are good healthy eating principles to base your diet on to achieve a healthy weight.

BMI outcomes in adults – Healthy BMI

Having a BMI reading of between 18.5 and 24.9 means you are of a normal weight and that your body is not at risk of a weight-related disease.

It is important to ensure that you maintain your healthy weight through a balanced diet of vegetables, fresh fruit and limited intake of processed food.

If your calorie intake matches your energy output you will remain a normal weight, but exercise is also important, with 30 minutes a day for five days a week recommended for all adults.

Keeping an eye on your waistline
can also help monitor any excess weight that might put you at risk of developing long term health conditions.

BMI outcomes in adults: Overweight or obese

If you have a BMI reading of over 25 then you would be classed as overweight, while a reading of 30 or above would see you measured as obese.

Being classed in these groups puts individuals at greater risk of potential risks and illnesses. Doctors may advise you to consult with a bariatric surgeon if your BMI falls in the obese category to help you instigate a weight loss regime.

Among the diseases and health problems that can be more likely to affect overweight or obese people include:

• 
  Type 2 diabetes
• Cardiovascular diseases
• 
  Stroke
• 
  Hypertension
• Some cancers (breast, colon and endometrial)

Steps to achieving a healthy weight

Fitness specialists will recommend programs designed to reduce your BMI if you fall into one of these groups.

They will also provide guidance and support over how to change your eating habits and exercise regime to efficiently achieve the best results possible.

Weight loss can improve your health and improve physical ailments such as back and joint pain upon shedding excess weight.

Exercise

Even losing a small amount of weight can benefit adults who are overweight or obese, and commencing with an excise regime can help you become a healthier weight.

Adults are recommended to engage in at least 150 minutes of physical activity a week, but adults who are overweight will likely need to exercise more than this to lose weight. This could be achieved through

cycling
,


running,

swimming

Diet

Eating fewer calories by swapping high-calorie meals and snacks for healthier options is an additional part of losing weight.

Swapping energy intake from fats and sugars for increased consumption of fruits, vegetables and whole grains will also assist with weight loss.

Follow-up appointments will often be recommended if your BMI reading is over 25 to ensure that your weight loss goals are being met.

If you are looking to reduce your BMI reading, or alter your diet to lose weight, there are a number of ways to change your eating habits.

It may be rather than the food you are eating, it is certain habits you have developed which are responsible for your diet not being as healthy as it could be.

Stick to a regular eating schedule

A regular eating schedule can help

regulate blood sugar levels, which is especially important for people with diabetes.

Delayed or irregular meals can commonly cause a stronger sense of hunger which can easily lead to taking in too many calories when you do eat. Skipping meals can have a similar effect.

Eat with others

Setting aside time to eat with others can assist with this schedule, and your body will start to recognise times of the day where it can expect to consume food.

Eating with others, while engaging in conversation, can also help you eat food slower, leaving you fuller after your meal and less inclined to eat soon afterwards.

Eat before you get too hungry

If you feel hunger pangs and you are not eating a main meal for a while, eating a healthy snack such as fruit or raw vegetables is an ideal way of keeping hunger at bay.

Allowing hunger to build can result in your overcompensating during your next meal and absorbing more calories in order to make yourself feel full.

Drink lots of water

Water can be especially filling, so drinking a large glass either before or during meal, or both, can help you feel less hungry during and after your meal.

Replace any soda or sugary drinks that may accompany your meal with water to eradicate excess calories.

Don’t eat late at night

Eating late at night, particularly excess calories that can be found in crisps and

chocolate, is a sure-fire way of putting on weight. Instead, make sure you main evening meal is filling and nutritious enough to fight off the temptation to snack during evening or night.

Green salads

When preparing a meal, make a green salad on the side to fill you up. This can also be done in a restaurant when ordering your food.

Asking for a salad on the side, or to replace a more starchy food that comes with your meal, such as chips, is a healthy way to brighten up your plate.

Bring your own lunch

It can be quite tempting to buy food when you’re on a lunch break at work, especially if a collection of food shops is nearby.

However,

bringing your own lunch
each day will allow you to monitor your calorie content, with many food establishments (even those presenting themselves as healthy) often packing a surprising number of hidden fats into their foods.

Note that to ensure you do lose weight as a result of exercise, you will need to ensure that your diet does not contain excess calories which could prevent your exercise from bringing your body weight down.

Aerobic exercise

It is recommended by the World Health Organisation that adults get at least 30 minutes of moderate aerobic exercise five days a week.

Alternatively, this can be 75 minutes of vigorous-intensity activity through the week.

Children should aim to take part in an hour of physical activity each day.

Swimming, running and cycling are all good examples of aerobic exercise, which serves to increase your heart and breathing rate.

Aerobic exercise does not lead to putting on muscle mass to the extent that anaerobic exercise does. For this reason, when you perform aerobic exercise, you burn off fat without putting much weight back on as muscle mass.

Note that there is nothing unhealthy on putting on muscle mass, it is just that those who need to see their weight dropping for motivation purposes may prefer to concentrate more on aerobic exercises, at least initially.

Anaerobic exercise

Anaerobic exercise includes lifting weights and other resistance exercises such as push ups or stomach crunches.

Anaerobic exercise is effective in lowering your BMI, but you may find that you don’t experience a drop in your weight in the short-term as an increase in muscle mass may see the scales showing the same weight even though you are actually burning body fat.

In the longer-term, however, as your muscles increase, you should start to notice that your weight, and therefore your BMI, begins to drop.

When working a muscle group, make sure you have a day’s rest before exercising those muscles again as this will allow your muscles time to recover and grow.

Research shows that combining both aerobic and anaerobic exercise to be successful towards weight loss as well as in improving insulin sensitivity in people with diabetes.

Portion sizes have increased dramatically over the last 20 years, which can lead to

portion distortion
when meals are being served.

Keeping an eye on your portion size is important as you can avoid excess calories that would qualify as more than one food serving.

To limit your portion intake, especially with bigger meals, deploy some tips which can help reduce your portion size, and subsequently any additional calories which could increase your BMI reading.

Share your food

If you are out for a meal and wary that the portion of food you have ordered contains more than one food serving, either remove some of the food from your plate before you start or stop as soon as you feel full.

Offer to share your food, if dining with company, or ask to have the food wrapped up for you to take home.

You can maintain a healthy weight by choosing the right number of servings from your chosen food group by not finishing your plate if it exceeds this number.

Eat sweets in small amounts

Sweets can be eaten as part of diets, but smaller amounts are the way to go if you are consuming high sugar or high calorie products.

Restrict your portions, especially in times of festivities such as

Halloween, as this will keep your

blood sugar levels
from increasing as well as keep you from putting on excess body fat.

Don’t have seconds

Seconds can often be tempting if you still feel hungry after a meal, especially if you are dining out at a restaurant such as a buffet.

However, this can lead to you consuming portions that could feed between two or three people, a sure way to increase your recommended calorie content.

Note that having high sugar levels can itself be a cause of hunger and so if you’re hungry despite having recently eaten, it’s best to allow the insulin to catch up before eating any more.

Restricting yourself from having seconds, especially if you are already full, will keep your BMI reading and body fat level down.