Introduction to Dieting and Weight Loss

This webpage on diet and weight loss with its references is available.

There is a vast array of information on healthy eating and weight management.

The enormous number of promoted regimes makes it hard to find a suitable diet and stick to it.

For the last generation or two there has been a rapid increase in those who are overweight (BMI >25) and those who are obese (BMI>30).

Video: Weight Loss - Sibutramine

The energy equation

  • Calories expended on exercise > calories in food = weight loss

  • Eat more calories than we Use = weight gain

All programs designed to achieve weight loss must utilise this e quation.

Complex factors affect how and why we eat and how efficiently we burn calories. These include:

  • hereditary factors
  • age
  • general health
  • emotional response to food

The pros and cons to every diet affect individuals differently.

  • Successful weight loss plans only work by changing the balance between calories in and calories out.
  • Increasing calories out is a key element and you need to increase your excercise.
  • You should aim to lose 400 - 800 g (1-2lb) each week.

Calorie Counting Diets

  • Controlling our intake by counting calories in everything we eat and drink is logical and scientific.
  • Many people find it difficult to keep counting the calories even when they have learned the calorie counts of their favourite foods and drinks.
  • You can find charts on and


Low-Carbohydrate Diets - Atkins Diet

At one time more than a million people in the UK were following low-carbohydrate diets particularly when this was popularised in the Atkins Diet but their popularity has waned.

Atkins Diet or just 'Atkins', is a well-known low-carbohydrate diet created by Dr.Robert Atkins from a diet he read in the Journal of the American Medical Association and utilized to resolve his own overweight condition. He later popularized the Atkins diet in a series of books, starting with Dr. Atkins' Diet Revolution in 1972.

Various factors, however, led to its dwindling success and the company founded by Dr. Atkins in 1989, Atkins Nutritionals bankruptcy in  2005, two years after the death of Dr. Atkins.

Dr. Atkins rejected the conventional advice instead asserting that the increase in refined carbohydrates is responsible for the rise in metabolic disorders of the 20th century, and that the focus on the detrimental effects of dietary fat has actually contributed to the obesity problem by increasing the proportion of insulin-inducing foods in the diet.

The Atkins diet involves the restriction of carbohydrates in order to switch the body's metabolism from burning glucose to burning stored body fat. Many incorrectly believed that the Atkins Diet promoted eating unlimited amounts of fatty meats and cheeses. This is a key point of clarification that Dr. Atkins addressed in the  revisions of his book. Although the Atkins Diet does not impose limits on certain foods, or caloric restriction in general, Dr. Atkins pointed out that this plan is "not a license to gorge."

An attraction of these diets is that they offer an unlimited quantity of protein foods such as meat, fish and eggs together with unlimited fats including butter but virtually no carbohydrates such as cereals.

  • Proponents of the Atkins diet believe that these diets reduce digestible energy.
  • Opponents believe that the Atkins diet is self limiting because it is not palatable long-term.

The British Diabetic Association could not recommend this solution as it could have adverse effects on the kidneys and heart.

Research has confirmed quick short-term weight loss with the Atkins diet but the medium (six months) and long-term loss is no better than other diets.

Low-Fat Diets

Fat 9 calories per gram than either carbohydrate or protein - 4 calories each.

  • No more than 30% of dietary calories should come from fat - a low fat diet would reduce this to a maximum of 20%.
  • The fat in the diet should be monounsaturated or polyunsaturated as found in oily fish or olive oil.
  • Saturated fats, such as in fatty meat or full fat dairy products should be reduced as much as possible.

High-Fibre Diets

Fibre is essential for good health with a recommended minimum of 20-25g / day.

Filling up on high fibre foods can achieve satiation whilst reducing high calorie foods.

They take time to eat and release glucose slowly into the blood which makes you less likely to indulge in snacks.

Bran, wholegrain cereals, bread, pasta, brown rice and vegetables are rich in insoluble fibre and fruit, oats, beans and peas are sources of soluble fibres.

Initial side effects of high fibre diets are flatulence, stomach noises, bloating and sluggishness but these resolve with time. Fluids are to be encouraged to avoid these problems. 

Glycemic Index (GI) Diets

GI diets revolve around the role of carbohydrates (sugar and starch foods) and in particular on the speed at which carbohydrates are digested into glucose and released into the circulation.

  • The concept originated in the care of diabetics where the objective is to prevent blood sugar levels rising too high. foods with low GI result in fewer peaks and troughs.
  • Diabetics are advised to include low GI foods with most meals.
  • The glycemic index is a classification of carbohydrates according to the speed they are digested.
  • Glucose is rapidly absorbed into the blood stream and has a GI rating of 100, spaghetti a GI o 41 and grapefruit 14.

The theory of low GI diets is that by using carbohydrates that have a low GI, hunger is reduced. Slimmer's on low-GI diets have little high-sugar, high-fat snacks but eat low-fat-high fibre food.

  • These diets conform with current concepts of a "healthy diet".
  • Low-GI carbohydrates (rating< 60) include most fruits and vegetables, wholemeal bread, porridge, rice, beans and peas.
  • High-GI foods which are to be kept to a minimum include white bread, white rice, sweet breakfast cereals, cakes and biscuits.
  • Proteins and fats have no GI rating as they are not altered into glucose. They do reduce the rate of digestion and this lowers the GI rating of meals.

Why is the Glycemic Index Important?

  • Your body performs best when your blood sugar is kept fairly constant.
  • If your blood sugar drops too low, you feel lethargic and experience increased hunger.
  • And if it goes too high, your brain signals your pancreas to secrete more insulin. Insulin brings your blood sugar back down, but primarily by converting the excess sugar to stored fat.
  • When you eat foods that cause a large and rapid glycemic response, you may feel an initial elevation in energy and mood as your blood sugar rises, but this is followed by a cycle of increased fat storage, lethargy, and more hunger!
  • The theory behind the Glycemic Index is simply to minimize insulin-related problems by identifying and avoiding foods that have the greatest effect on your blood sugar.

How Glycemic Load Improves the Glycemic Index

Although most sweets have a relatively high glycemic Index, eating a single amount will result in a relatively small glycemic response because your body's glycemic response is dependent on both the type and the quantity of carbohydrate consumed. This concept, known as Glycemic Load, was first popularized in 1997 by Dr. Walter Willett and associates at the Harvard School of Public Health. Glycemic Load is calculated this way:

GL = GI/100 x Net Carbs

(Net Carbs are equal to the Total Carbohydrates minus Dietary Fiber) Therefore, you can control your glycemic response by consuming low-GI foods and/or by restricting your intake of carbohydrates.

Limitations of the Glycemic Index and the Glycemic Load

Some proponents of the Glycemic Index would like us to believe that GI and GL are all that matters when selecting which foods to eat. In reality, diet is a more complex issue than that. However, there are also many limitations to GI and GL.

  1. Scarcity of GI data
    Although methods for determining Glycemic Index have been in existence for more than 20 years, GI values have so far only been determined for about 5% of foods.
  2. GI values affected by preparation method
    Generally, any significant food processing, such as grinding or cooking, will elevate GI values for certain foods, because it makes those food quicker and easier to digest. This type of change is even seen with subtle alterations of the preparation, such as boiling pasta for 15 minutes instead of 10.
  3. GI values affected by combination with other foods
    While tests for Glycemic Index are usually done on individual foods, we often consume those foods in combination with other foods. The addition of other foods that contain fiber, protein, or fat will generally reduce the Glycemic Index of the meal.
  4. Individual differences in glycemic response
    The rate at which different people digest carbohydrates also varies, so there are some individual differences in glycemic response between individuals.
  5. Reliance on GI and GL can lead to overconsumption
    It's important to remember that the Glycemic Index is only a rating of a food's carbohydrate content. If you use GI and GL values as the sole factor for determining your diet, you can easily end up overconsuming fat and total Calories.

Apples have a GI of 38 (as shown in the table above), and a medium-size apple, weighing 138 grams, contains 16 grams of net carbohydrates and provides a Glycemic Load of 6. This is a low GL, and most would consider the apple to be a very appropriate snack. But now look at peanuts. A 4-oz serving not only weighs less than the apple, but has a much lower GI (14), and provides an even lower GL of 2. Based on Glycemic Load alone, you would have to believe that the peanuts were a better dietary choice than the apple. But if you take a look at the Calories contained in these two foods, you'll see that the apple contains approximately 72 Calories, while the peanuts contain more than 500! Those 400+ extra Calories are NOT going to help you lose weight.

Mediterranean Diet

  • Diets in Greece, Spain and Italy are associated with healthier and longer life.
  • These diets are rich in fruit, vegetables and fibre. It is high in monunsaturated and polyunsaturated fats and low in saturated fats.
  • Sugary foods are rarely eaten.

Detox Diets

Promoters of detox diets claim improved skin, reduced cellulite, increased energy and a feeling of wellbeing.

  • The theory is that the body needs a boost to remove toxins including  caffeine, alcohol, nicotine and food additives.
  • These diets ban processed food, meat and dairy products, caffeine and alcohol.
  • Organic wholefoods, fruit and vegetables, seeds, nuts, juices and a lot of water drinking are encouraged.
  • These deits are low in calories.
  • They are popular kick-start methods for weight loss.
  • Medically, we believe that the underlying theory is invalid as the body has effective mechanisms for eliminating the toxins in question.

Diuretic Diets

  • Some people feel bloated or puffy and attribute this to fluid retention.
  • These aim to reduce fluid retention.
  • Diuretic diets include watery foods such as citrus fruits, melons, and diuretic herbs such as parsley.
  • Salt in the diet is restricted.
  • These diets are not specifically designed to reduce weight.

Food-Combining Diets

The theory behind these diets is that proteins and carbohydrates cannot be efficiently digested at the same time.

The Hay diet means that no meat pies or meat sandwiches can be eaten and fish and chips are banned.

Fruit must be eaten by itself.

Elements of these diets are consistent with "healthy eating" as they commend plenty of fruit and vegetables.

They are not particularly appetizing and so they are difficult to sustain.

Crash Diets

see Mayo Diet

Food intolerance diets

Many believe that they have an intolerance to certain foods although for the majority of these, there is no objective supporting evidence.

True food intolerance is more likely to result in weight loss than weight gain.

High Fat Diets

Conventionally we believe that low fat in the diet is best suited to weight loss but some promote the opposite.

The theory is that reducing carbohydrates in the diet causes the body to burn its fat stores.

Most dieticians compare these diets to pouring oil on a fire.

Anti-cellulite diets

Cellulite is the colloquial name for lumpy fat that causes the skin to look like orange skin. It particularly accumulates at the thighs and bottom and is more of a problem for women than men. There is no good explanation for cellulite rather than normal fat deposition. Some blame it on toxins or a lymphatic drainage problems. Accordingly, detox diets have been recommended although there is no scientific foundation for this.

Meal Replacement Diets

These reduce energy intake by replacing one or two meals with a low calorie but balanced substitute such as a milkshake or soup etc.

Hypnotherapy to Assist Dieting and Weight Loss

Hypnotherapy may influence the mind to change habits including over eating.


This form of "healing" has been practised in China for many centuries. Fine needles are inserted in meridians intended to stimulate the body's natural healing properties.  The objective is to enhance "the balance between the physical, emotional and spiritual harmony" which may have been upset by one of many factors including anxiety and stress.

Prescription Drugs - Xenical - Reductil

These are discussed on Weight-Loss-Dieting


  • In the USA more than 100,000 operations are performed each year to assist weight loss whereas in the UK these operations have not become popular.
  • Gastric banding results in a ring at the top of the stomach restricting food intake.
  • Gastroplasty causes the stomach to be partitioned in two. The small segment fills quickly and then empties slowly into the second section.
  • Bypass operations restricts the size of the stomach and bypasses some of the absorbing areas so that fewer calories are absorbed.

Slimming Clubs

The UK slimming clubs have more than a million members with about 90% being women. They offer eating plans and exercise programmes. Many have websites where additional information can be found. Weight gain can be a result of comfort eating related to stress. Everyone is subject to stress but when it becomes difficult to cope with, counselling or psychotharpy can resolve the underlying issues.


  • Reducing calorie intake alone can result in weight loss but exercise can help burn calories and may have a significant benefit for those seeking to lose weight. You can also have fun shaping up.
  • Modern life style in developed countries is hostile to people who wish to control their weight. Most of us have sedentary jobs, drive cars instead of walking, use labour saving devices and spend our leisure time watching the TV or going out for meals.
  • The recommended level of exercise to maintain health is 30 minutes of moderate activity each day for at least 5 days each week. Between 30-50% of us fail to undertake this amount of activity.
  • The Chief Medical Officer for England in a report in 2004, concluded that physical inactivity is just as important as smoking and an unhealthy diet in the risk that it poses to health and wellbeing.
  • The report also showed that adults who are physically active have a20-30%  reduced chance of dying prematurely from any cause and are50% less likely to develop heart disease, stroke, diabetes and cancer.
  • Undertaking regular exercise is essential for those who wish to have along and healthy life.
  • A negative balance of 400 calories per day will result in a weight loss of one ounce (of fat) - about 1/2lb each week. Of course, if you start a diet with very little food, your bowel will become less full and this appears to provide a rapid weight loss which of course cannot be sustained.
  • It may be difficult to reduce your calorie intake by 400 calories per day but more realistic to decrease it by 200 calories and increase your exercise by a further 200 calories.
  • Feel good factor.Strengthening the muscles through regular exercise tones them up sop that the body looks trim.
  • It makes you feel uplifted and more confident.

    Table: Activity and Calorie Expenditure

    Activity Calories used in 20 minutes
    Dancing 80
    72 steps / minute 95
    Cycling - flat ground 125
    Golf 100
    Squash 200
    Tennis 140
    Football 140
    Running 190

Boosting Metabolism

  • Exercise tends to replace fat with more muscle and this boosts the body's metabolism.
  • One pound of fat tissue burns 2 calories each day compared to 35 calories for 1lb of muscle.
  • Thus exercise has an immediate effect on weight loss but a longer term benefit as well.


If you are overweight your fertility will be reduced. This is true for both men and women. It is unclear whether it is the weight that is an independent factor for women or whether other factors such as polycystic ovary syndrome (PCOS -Q7.2) result in both the infertility and excess weight. At the other extreme, if you are under your ideal weight you are more likely to have anovulation problems . The Body Mass Index (BMI) is a ratio used to compare your weight with your height. The BMI is calculated as indicated in Table 9.1.


Table 9.1  Calculating your Body Mass Index.

BMI = Weight (Kg) / Height (m)2.

Your BMI should be between 20 and 24. If your BMI is less than 20 you are underweight. You should lose weight if your BMI is between 25 and 29. You are considered to be medically obese if your BMI is 30 or more and you would be regarded as very obese if your BMI is greater than 40.

Table 9.1

Weight Kg and


Height in metres and (ft ins)s)

Height (m2)



(7st 110lb)


(5ft 4ins)


18 (49 / 1.632)


(9st 9lb)


(5ft 2ins)


24 (61 / 1.582)


(14st 2lb)


(5ft 6ins)


32 (90 / 1.682)


(16st 10lb)


(5ft 1ins)


44 (106 / 1.552)



    Women's Health

    This is the personal website of David A Viniker MD FRCOG, retired Consultant Obstetrician and Gynaecologist - Specialist Interests - Reproductive Medicine including Infertility, PCOS, PMS, Menopause and HRT.
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    I do hope that you find the answers to your women's health questions in the patient information and medical advice provided.

    The aim of this web site is to provide a general guide and it is not intended as a substitute for a consultation with an appropriate specialist in respect of individual care and treatment.

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