There not many of us who have not experimented with fad diets at some point in our lives. Most of us feel so ecstatic when we see the kilos drop, the faster the better! We hardly ever worry about the science behind the eating plan or the reason why we are losing weight. Please read on to discover the truth about some popular fad diets…
Low Carbohydrate / High Protein Diets
Dr. Atkins’ “New Diet Revolution” is a well known low carbohydrate diet. In 2003 Dr. Atkins’ “New Diet Revolution” outsold every other book in the UK by a factor of 3:1 (“Harry Potter and the Order of the Phoenix” was second). Every magazine and TV show talked about it; fantastic claims of magical weight loss abounded; celebrities endorsed it. Yet what does the diet actually consist of?
In essence, the diet allows unlimited amounts of protein and fatty foods (including meats, eggs, cheese, cream, etc.) but severely cuts back on foods rich in carbohydrates. Dr. Atkins (himself a cardiologist) states that by following this diet, we can change our metabolism and lose weight quickly and easily. Too many carbohydrates, he says, causes over production of insulin, leading to increased hunger and weight gain. Carbohydrates are therefore severely limited in the diet, while protein and fat are allowed in unlimited amounts.
There is certainly some truth in what he says, and those who had previously tried an opposite diet (i.e. low fat, high carbohydrate) without success found the Atkins diet highly effective and rated it as very easy to follow as there safe no complicated meal plans. They enjoyed the fact that normally ‘banned’ foods were allowed.
Low carbohydrate diets lead to a reduction in glycogen storage. Because glycogen is stored together with 3-4 times its weight in water, much of the rapid weight loss experienced may merely be fluid loss. Once carbohydrates is eaten again all the body water weight that was lost may instantly be gained again.
However, there are many questionable aspects of the diet when long term healthy eating is considered. For example:
- There have been claims that it may be a problem for those with weak kidneys
- The American Heart Association has released a statement saying they do not endorse it
- The diet is deficient in certain vitamins and minerals
- The diet is deficient in fibre
- The diet is deficient in many antioxidant phytochemicals found in whole grains and fruit
- Most of the foods allowed are expensive
- The diet can be high in saturated fats
- The Atkins diet is not suitable for the regular exerciser. High carbohydrate diets have consistently been shown to be beneficial for athletes. For regular exercisers, ketosis (inefficient breakdown of fats because of too little carbohydrate) is a risk, together with muscle wasting, leading to a drop in BMR.
Blood Group Diet
This diet is based on the idea that each blood group (A, B, AB, O) has a unique antigen marker, which reacts badly to certain kinds of food. It is therefore claimed that by following a diet based on your blood group, your digestion will improve and this will encourage weight loss.
Scientists have theorized that the different blood types evolved over time. For example, they say: type O first appeared when man was a big meat-eating hunter; those with type A appeared when people began farming; and both types B and AB descended from nomadic people who ate a bit of everything. Each individual has different levels of digestive enzymes and stomach acidities closely related to blood group. Each of the four blood types therefore has a list of foods that should, in theory, be avoided.
Despite the popularity of the diet, there is no evidence at all that blood group affects the foods we can eat, and whether those calories will be stored as fat. Instead, there is mounting genetic evidence that blood groups are strongly linked to natural immunity to endemic diseases such as malaria and cholera, not to food.
The diet is certainly an interesting idea. It is ‘novel’ and ‘different’ and therefore attractive to habitual dieters. But it has not been shown to affect body weight or fat deposition, unless of course, it is hypo calorific.
There are strict guidelines to be followed, such as what to eat/not to eat, and when. This regimented approach appeals to some. It is less practical, however, if one or more people in a household have different blood types, causing each of them following a very different diet. Finally, following the diet strictly leads to some foods being completely missed, which can result in nutrient deficiency.
Food Combining Diets
There are several diets based on this theme. The theory is that combining foods inappropriately means that they cannot be absorbed into the intestinal tract and that weight gain is a result of eating patterns not excess calorie intake. The main two food groups that should not be eaten together are starchy carbohydrates and proteins. This is because starchy foods require lower stomach acidity for digestion, compared to proteins. This is because starchy foods require lower stomach acidity for digestion compared to protein foods. Eating them separately at different meals allows full digestion; eating them together means only partial breakdown, poor absorption, and hence a number of health problems. Therefore, combinations such as steak and chips, spaghetti Bolognese, or a ham sandwich, are banned. Dairy products are often prohibited as well.
There is no scientific evidence to support the validity of this dietary approach. Millions of people eat mixed meals all the time with no ill effect. Mixed meals are universally consumed in all cultures and at all socio economic levels.
Participants claim that food combining diets are very effective if followed closely, with weight loss noticeably occurring. However, this is more to do with restricted calorie intake, rather than maximizing the body’s digestive powers. Weight loss occurs rapidly due to the limits on food types allowed.
Most of the foods allowed are fruit and vegetable, the rest consisting of one or two servings of starch (such as rice or pasta) and minimal amounts of animal protein. Whilst eating more fruit and vegetables is widely encouraged by most health authorities, drastically restricting other food groups is not. Unfortunately, the diet is deficient in many nutrients including protein, calcium, zinc and vitamins D and B12 and cannot be recommended for this reason.
Meal Replacement Products
Meal replacement products usually come in the form of shakes or nutrition bars, which the person eats in place of a normal meal. They are usually full of all the necessary vitamins and minerals, proteins and carbohydrates, whilst being low in fat and low in calories (170-220kcal each). Hence they can aid in weight loss. One of the best known brands of meal replacements claim that their products are: “an easy, nutritious, convenient, economical, great tasting, simple and flexible method for weight loss and weight maintenance”.
The basic plan uses two meal replacement shakes, three snacks and one sensible meal each day. This should result in weight loss of 0.5 – 1kg per week. The calorie intake is approximately 1200 calories per day, and in addition, daily exercise of 30-60 minutes and lifestyle changes to promote long lasting weight maintenance are encouraged.
Meal replacement products can be a useful approach to weight loss for some people. Their main strength is convenience: the dieter need only take two shakes or nutrition bars to work with them, and then cook a meal in the evening. They are assured of a reasonable micronutrient intake.
There are several possible drawbacks:
- The products are expensive
- Not everyone can tolerate the taste on a repetitive basis
- The diet is very restricted in calories for anyone with a large build
- Relying on highly processed shakes and nutrition bars does not promote long term healthy eating.
Fad diets can be a shock to the system, and our bodies do not like to be shocked. Each time we starve ourselves or deprive ourselves of a certain macronutrient, our bodies will desperately hold onto everything you eat again after the starvation and store it in case you decide to do such a horrible thing again. Any food that is stored in the body is stored as one thing only: fat. That is why we always experience the yo-yo effect in between fad diets.
Our bodies have been designed to eat food and needs all the different macronutrients to function properly, ideally 55-60% carbohydrates, 30-35% fats and 10-15% protein . It is ideal to have 3 balanced meals with 2 healthy snacks each day, and keep it as natural as possible. Make a healthy, balanced meal plan part of your lifestyle. And remember, if you want to lose weight, always start by incorporating regular exercise into your daily routine. If you are a regular exerciser, increase your workout intensity.
If you are unsure about how many calories you are allowed per day and how to work out how many calories can come from each food group, see a Nutritionist who will be able to give you a good guideline based on your individual goals.