Meal-plans form the basis of all weight loss programmes. At the Institute, we are often surprised at how much people are prepared to pay for these “pieces of paper” containing some very basic information. It’s almost as though some believe that a meal-plan, like wearing a rabbit’s foot around your neck for good luck, possesses certain magical properties to fast-forward you towards your ideal figure with a guarantee of success. If you look at many statistical trails conducted on weight-loss, this is rarely the case.

Although the information on a meal-plan is relevant, its real value lies in its execution.  Upfront decisions need to be made concerning its practicality, affordability and most importantly, sustainability.  Many meal-plans are based on sound scientific principles, yet there are also those veiled in pseudo-scientific mumbo jumbo. To assist you in unravelling their mystery elements, we will discuss a few of the most popular diets:

Mono food diets
There are many versions of these diets, examples being the soup diet, fruit diet, grape diet, etc. Few people can sustain these diets for long as they become painfully boring. They are mostly unbalanced and nutritionally deficient, lacking certain food groups or food components. Except for the “orange food only” diet, (which allows you to eat salmon with your carrots, oranges and pumpkin), these diets are too low in protein, meaning that you will lose some of your muscle over time, lowering your metabolic rate.

Our Verdict: - most of these diets, with perhaps some minor improvements, can probably be used as a detox process by those interested. If used at planned intervals, they are also useful in breaking the monotony of a regular diet.


Very low kilojoule diets (Less than 1000 Calories / 4200 KJ per day)
These are based on the assumption that the less you eat, the more weight you will lose. Unfortunately it does not quite work that way, as your body sees the process as famine and lowers your metabolic rate. In addition, it may also cause you to burn your muscle for energy purposes, further lowering your metabolic rate.

Our Verdict: - there are some cases in which the medical profession have no alternative option but to use this diet. Very few people are able to stick to it without the assistance of an appetite suppressant.

Very low fat diets
This diet is based on the assumption that the less fat you eat, the more weight you will lose. Ironically it’s not that simple, as essential fatty acids play a critical role in controlling the secretion of insulin (the fat producing and fat storing hormone). If fat needs to be burnt in the body’s energy furnace, small quantities of fat are required to assist this process.

Our Verdict: - there are many extremely health conscious people who will take to this diet like a duck to water. It is a bit too extreme and self-obsessive for our liking.

Food combining diet
This is based on a school of thought which says protein and carbohydrates should not be eaten at the same time. Dietetic scientists do not agree with the logic behind this eating style as mixed meals containing fat and protein, slow down the overall glycemic index, thereby controlling your hunger for longer periods. To complicate the issue further, all protein sources contain carbohydrate. Glycogen, the store form of glucose, is present in muscle. All meat (muscle) sources therefore contain some carbohydrate. Most carbohydrates, on the other hand, contain small quantities of protein. A good example of this is the protein “gluten” in wheat. Eating ‘more meat’ means that you also eat ‘more carbohydrate’ in a minor way, and vice versa.

Our Verdict: - Some report they have less stomach problems like heartburn and bloating if they follow this eating style. Others lose weight because of energy restriction and a more disciplined eating style.

Blood group diets
This diet is based on an opinion that we should eat according to the genetic programming of our prehistoric forefathers, explaining how they became conditioned to certain food substances during their evolutionary migration period. Not supported by the scientific community. It’s a highly fragile eating style, quite impossible to follow in a family of three people or more - all with different blood groups and needing to eat different food items. Imagine you being the one responsible for preparing such a meal!

Our Verdict: - We agree with the scientific community.

High protein, low carbohydrate diets.
These diets all restrict carbohydrates to varying degrees. Those with large appetites are allowed to consume larger portions of protein, hence the “high protein” part of the title. These diets often also require you to check for ketones in the urine. The reason for this eating style being effective is that it lowers insulin levels. Because carbohydrates, especially large quantities of the high GI group raise blood insulin levels and precipitate the deposition of fat, doing the opposite ( excluding them from your diet) will keep your insulin levels low and help you lose weight. The so-called ‘ketogenic diet’ or high protein diet takes this process to the limit and only type 1 diabetes can lower your serum insulin levels further. ‘Lipolyses’, the medical term for ‘fat-breakdown’, is music to the ears of those with excess weight. As fat molecules are broken down for energy purposes, small carbon-containing molecules (called ‘ketone bodies’) are released. The process is therefore called ‘ketogenesis’. The ‘ketogenic diet’ says it all – fat is being broken down!

Our Verdict: - Although many people feel well on these diets and are satisfied with their weight loss results, there are others who report they feel tired and listless. It may precipitate an attack of gout in those who are susceptible as well as gallstones in those who already have them. It can also place a heavy toll on the kidneys. Eating more than 80g of pure protein a day, (which equates to 350g of meat, fish, chicken or cheese) increases your risk for osteoporosis.

High protein, high fat diets.
This diet corresponds to the one above but includes more fat. You are, for example, not required to remove any visible fat off of your food and may add cream to your coffee.

Our Verdict: - Far too extreme for our liking. If you are a food connoisseur who loves high fat dishes like marrow bones on toast, fois gras and calf’s brain in cream, this diet will suit you like a glove.

The GI diet.
The Glycaemic Index (GI) classifies carbohydrates according to the speed at which different food items release glucose into the system, as well as their ability to raise blood glucose levels. Rising blood levels are directly linked to blood insulin levels.  Food items with a low to intermediate GI value raises blood glucose levels much slower than food items with a high GI value. If glucose enters the system at a slower rate, less insulin is also secreted. The result being - less fat is deposited.

Various factors affect the rate at which glucose is released. Individual properties relating to the food substance, the presence of fat, fibre and protein in a mixed meal and different food production and processing techniques, all determine how quickly each food substance will be digested and release its glucose content. Besides worrying about the Glycaemic Index, you also need to consider the Glycaemic Load. This stipulates how much energy each carbohydrate item contains.

Let’s look at a practical example; will a slice of watermelon, high in GI but low in GL, or a slice of seed loaf, low in GI but high in GL, benefit you the most when trying to lose weight? In other words, which is more important:  the glycaemic index or glycaemic load?

The answer lies in the amount of energy released. The best way to lose weight is to reduce the total amount of energy you consume. The Glycaemic Index, however, will give you a competitive edge.

Our Verdict: - this is mainstream stuff, especially for weight maintenance purposes. What complicates it a bit is that we mostly eat mixed meals and the presence of fat, fibre and protein in a meal changes a food item’s GI value entirely, usually lowering it. This can all become rather confusing.

Carbohydrate diminished, energy restricted diet.
The ketogenic diet allows you to fill your stomach, albeit with more protein and fat and virtually no carbohydrate, instead of just eating small balanced portions of everything. It is therefore referred to as a ‘high protein diet’. But, as usual, things are not quite that simple. Let us imagine that someone ate too much food. This person ate, on average, certain quantities of protein, carbohydrate and fat within a day, (in a X:Y:Z ratio for example). If this person ate less food, (only less carbohydrate), the X:Y:Z ratio would change. In other words, the fat and protein ratio would now be higher than before. Using the term ‘high protein diet’ to describe this person’s new diet is not correct, hence the term ‘carbohydrate diminished’.

Our Verdict: - we have found this diet very effective.

Meal replacement diets
Many shakes contain as much energy as an entire meal. The question is, wouldn’t you then prefer to eat proper food? We’ve had many cases where patients on the Lighthouse weight-loss system™ have battled to lose weight, only for us to find upon investigation, that they were using meal replacements or slimming shakes. Once these were stopped, their weight-loss results improved dramatically.

Our Verdict: - For people on the run, meal replacements can form a good substitute for breakfast or lunch on occasion.
What does the latest scientific research say?
In a landmark study reported in the prestigious New England Journal of Medicine, researchers examined the efficacy of different weight-loss diets. They found that most diets were successful, with not much difference between them, and that weight loss achieved with diet was similar to the weight loss result that can be achieved with medication.

Their observations led them to conclude that behavioural factors, rather than macronutrient composition, are the main influences on weight loss.

Their verdict: “We do not need another diet trial; we need a change of paradigm.”
Sacks et al.

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