The word ‘diet’ can mean both what you eat and drink in general terms or a specific, prescribed nutrition programme that you’ve elected to follow often, but not necessarily, to lose weight, so its usage can be confusing. In general, your diet – in the general sense – should consist of an appropriate balance and quantity of macro nutrients (carbohydrates, protein and fat) and micro nutrients (vitamins and minerals). This is a subject we will turn to in depth in a future article.

For now, suffice to say that creating your own ‘diet’ from fundamentals does require a little knowledge and effort, so it’s tempting to adopt a pre-packaged one, where someone else has done the thinking for you.

There’s also the peer pressure problem. How often after a swimming session have you heard comments like, “since I stopped eating bread, I’ve lost 5kg” or “my times have really improved since I started on the XYZ diet.” This problem can be particularly acute if you hang out with triathletes. The danger with this is that you rush to copy your colleagues based on these anecdotes rather than the real evidence of a particular regime. It may also be the case that the claimed benefits have different causes.

In the last issue of H2Open, part one of our series on real life nutrition looked at ten different nutritional philosophies/diets. In the article we reviewed each in turn and examined what foods they encouraged or discouraged respectively, claims for and against each of them and also gave an example quote, which gave a suggestion of why swimmers and athletes from other sports might consider choosing one over the rest. In this extended, in-depth article (Too long for the magazine so it’s here online), we will scrutinise the same ten nutritional philosophies, ranking them according of their usefulness to you, the open water swimmer. This will be achieved by examining the science behind each and referring to experts in human nutrition – you may well be surprised by some of the findings!

You may not be on a ‘diet’ in the general sense of the word, however, just as we plan, keep and review a training diary, if we are to achieve our goals in sport it is just as – if not more – important  that we also have a plan for what we eat and drink on a daily basis. Each of these nutritional programmes offers a framework for our day to day eating habits and it is the aim here to establish which is the best framework for you to build your diet around.

It would be helpful if you have read part one in the last issue before this online follow-up, however, if you are new to the magazine, don’t worry too much, part two should be easy to pick up.

As with the Atkins diet, the recent research showing that high fat diets hold many health benefits as well as possibly helping to improve sporting performance is paradoxical. Nonetheless, these findings are conclusive with a vast array of studies showing their benefits. 

A significant review of the current data published in Spain in 2010 stated that ‘, but that a ‘. 

The author, Ramon Estruch, from the Department of Internal Medicine at the University of Barcelona continues . Diseases including many forms of cancer and CVD thrive in the body when food choice and/or a lack of exercise have produced an inflammatory environment. This report continues highlighting the MED diets ability to reduce inflammation, thereby having an effect on both risk and treatment of such conditions as well as positive effects on blood pressure, obesity and diabetes. Omega 3 oils (found in fish such as salmon and mackerel) are high in the MED diet and these may also be beneficial to exercise with three studies showing increased blood flow, one showing increased red cell health, two showing reduced HR during lower intensity exercise and one showing reduced muscle soreness. There needs to be more research in this area, but it seems that the MED diet may well support and enhance physical adaptations as a result of training. 

Crucially, while Atkins and the Paleo diet typically reduce carbs while increasing arbitrary fat intake, the MED differs by promoting the ingestion of the ‘good’ fats previously discussed. Where the diet also differs is through the freedom it gives to match carb intake to individual needs. For the less active person keen to be as healthy as possible, it can easily be a low carb option, however for those involved in harder or more regular training, some carbs in the form of whole grain breads, pastas and cereals can be added to the core components of olive oil, fresh fruit and veg, oily fish, walnuts and moderate red wine consumption to make a bespoke diet, the benefits of which are fully supported by scientific research.

In its original form, the Paleo Diet is similar to the Atkins Diet – with an emphasis on meat – and the Alkaline Diet as it aims to regulate blood acidity (however, it’s worth pointing out that there is a contradiction between the Alkaline and Paleo Diets as the former excludes meat). A study by Frassetto (2009) found that the Paleo Diet had a positive impact on various markers of health including blood pressure and also how the body deals with blood sugar. 

Whilst it is important to realise that the diet was being tested against a typical modern American diet – which has rendered the country with obesity rates of 35.7% – and also that these markers of health are generally improved by weight loss however it occurs, there may well be some support for its use. What is more relevant  to swimmers are the changes made to the diet in the last 5 years by world leading triathlon coach Joe Friel, making it more appropriate for endurance athletes. Curiously, these adjustments actually remove this new version of the diet fundamentally away from its original principles. For example,  In the book ‘The Paleo Diet for Athletes’ it is states that . 

However, according to the book, meals in the few hours before, during and up to 90mins after exercise should contain carbohydrates, resulting in the ‘Paleo Diet for Athletes’ becoming very close to the classic balanced diet of 55/20/15% carb, protein and fat. An area of concern would be the author of the Paleo Diets affirmation that replacing salts is  which flies in the face of the majority of research and could lead to the development of a condition known as hyponatremia or water intoxication, which can lead to dehydration-like symptoms and even death.  That said, while true Paleo Diet is probably a poor nutritional choice, the modifications made by Mr Friel, change it significantly and certainly enough to be considered a reasonable choice for the athlete looking to maintain body composition and performance.

Despite superseding the GI diet, the use of the GL diet as a nutritional philosophy is still unfounded and controversial in the eyes of some researchers. A systematic review of relevant research from 2008 stated that . 

This is impressive, however other studies have found less association between chronic disease and a diet composed of low GL foods. This leads Professor Janice Thompson from Bristol University and fellow of the American College of Sports Medicine to conclude ‘For swimmers, who require foods that raise blood sugar levels immediately before, during or after exercise in combination with sustained energy outside of training, it is important to understand the effect certain foods will have on blood sugar levels and In this regard, the principles of the Low GL diet are highly useful to the open water swimmer. 

Where the diet suffers is its complexity, also that it could lead to less of a focus on the intake/quality of protein and fats, which might be damaging to heath and negate the benefits offered by more constant blood sugar levels. Nevertheless, whichever nutritional philosophy is chosen, an understanding of the GL scale is important for athletes at all levels. 

The development of the GI scale has been useful in understanding the effect of foods on blood sugar; however, it has some significant flaws which Professor Thompson explains:he continues, ‘(However) 

This shows that the theory of the GI scale may still bring about positive health changes for athlete and non-athletes alike, yet it has come under much criticism as the way that the food is prepared, how ripe it is and also it’s fat or fibre content all affect its effect on blood sugar. Professor Thompson also highlights that it is ‘This makes real life calculations of GI hard, and it’s poor accuracy mean that it should not be used as the yard stick for what we should and shouldn’t consume. 

However, like the GL scale while it also focuses on carbohydrates, leaving the amount and type of fat, protein, vitamins and minerals less well directed, it is a very useful guide for athletes and helpful for educating people about the effects some foods have on blood sugar.

Weight Watchers is the world leading provider of weight management services and has been shown to be . However, how does it fair as a lifestyle choice for the open water swimmer wishing to maintain weight? A relevant strength of the programme is that it provides a framework encouraging good eating behaviours, a fairly even intake of energy over the day and also educates adherents about portion control. This is crucial as portion control and an understanding of what ‘normal ‘ looks like is at the heart of many dietary related problems in the western world. Adherence to the diet is also high with a study by Dansinger in 2005 showing adherence over one year to be higher than several other major diets including Atkins, supporting its use as a lifestyle choice. The other side of this however, is that swimmers might end up learning what points certain foods ‘score’ rather than what is healthy for them. Further, there is a focus on total energy intake rather than the ratio of carbs, protein and fats – important to the athlete, and there is little guidance on timing of foods with respect to exercise – also crucial for active individuals looking to maximise their performance and recovery. Lastly, while the Dansinger study showed that the ratio of saturated fat to other fats was better than Atkins, Weight Watchers does not overtly encourage the intake of healthy omega 3 fats and olive oil over spreads and oils that contain vegetable oil, and this could lead to the inflammatory environment highlighted by findings associated with the Mediterranean  diet  (see article in Feb/March 2012 issue). Nevertheless, Weight Watchers’ ability to produce changes in behaviour that support long term weight maintenance – as observed by O’Neal et al, 2010 – do render it particularly useful for swimmers who struggle to maintain a consistent weight and who have a limited understanding of dietary issues.

Low carbohydrate diets (LCDs) – typified by the model of the Atkins Diet – were originally thought to be a fad, however, it is now 39 years since it was first forwarded as a concept and there is still much debate as to the effectiveness and consequences of following a diet that illogically often results in a high fat intake and yet produces weight loss. While there is much evidence to suggest that LCDs are effective at promoting weight loss, a recent Norwegian review of these diets showed that ‘’. It also highlighted that initial weight loss may well be as a result of ‘ ’ and that a long term reduction in weight was due to less consumed calories rather than a direct result of a reduction in carbohydrate. 

The main issue here though is whether or not the diet is appropriate to those participating in open water swimming; and some studies show some very interesting results in this area. Well established over the last 30 years or so is a vast body of research that suggests that sporting performance and recovery is improved by a high carbohydrate diet. However, there is also a growing body of more recent work suggesting that LCDs where fat intake is not restricted do not harm (and may even enhance) endurance exercise between 60-70% of max effort. These results are particularly significant for swimmers with type 2 diabetes as this type of diet may well not decrease performance as once thought, while also helping to maintain consistent levels of blood sugar. 

Further, a paper by Manninen (2006) observed several findings showing that a low carb diet promotes fat loss while maintaining lean muscle mass, an observation crucial for swimmers who want to lose weight but maintain swimming ability. The issues with this approach are twofold. Firstly, while swimmers might maintain muscle mass and reduce body fat while on a LCD, this is not that same as maintaining aerobic muscular fitness which will be compromised as training above 60-70% of max effort will suffer, equating to a total reduction in functional fitness over the period on the LCD. Secondly, if – as observed in the article by Manninen – total calories and protein are kept the same and participants are placed on either a high fat/low carb or high carb/low fat diet, while the high fat diet might produce significant weight loss and maintain muscle mass, as previously mentioned we also need to know what types of fat are being consumed. In the case of Atkins, research published in 2005 clearly shows that saturated fat intake is almost double that of several other diets including Weight Watchers – showing that the diet can elicit poor food choices. Saturated fats have been shown to have many negative health consequences so a focus on choosing good fats is crucial for Atkins followers (see Anti-inflammatory Diet).

Like the Atkins Diet and as highlighted in the last issue, one major factor for consideration with this dietary philosophy is that – on a basic level – while it excludes some foods it does not require the follower to ensure a healthy consumption of the foods that are permitted.  When commenting on how this might affect the vegan athlete, Mark Hobden – Human Nutrition Researcher at the University of Reading and Performance Nutrition Ltd gave this in-depth insight on the subject for H2Open.

In his book, ‘Bloodtype Diet O: a custom diet for losing weight’, Dr Joseph Christiano states . This may well be true; however, there is a sense that this statement is included to explain away the fact that – in the words of one nutritionist – ‘Dr Chirstiano continues . 

However, can and indeed should we ‘all agree’ with this? Firstly, this statement pre-supposes that certain foods interact differently with our bodies depending on our blood type, but there is simply no peer-reviewed studies that validate this. Further, while the theory may well be more individualised that a one size fits all approach such as many Very Low Calorie Diets (VLCDs), it is not nearly as individually specific as nutritional philosophies that can be manipulated in any number of ways such as GL. Rather, for an athlete, instead of being ‘individualised’, the diet might well be inappropriate for athletes who need to be able to manipulate their diet to meet the demands of the level of activity, atmospheric temperature, altitude or recovery status. 

In the original book Eat Right for you blood type by Dr D’Adamo, the description of how certain blood types ‘evolved’, has also been widely criticised both in its core concept and also the order he states different blood types came into being. Further, no evidence is given for why some foods are banned or limited while others are not. While some of the 5 million people who have bought this book might well have reported some benefit from it, it is more likely that this is from structuring a diet that had previously consisted of an ad-hoc intake of foods rather than as a result of actually tailoring food to ones bloodtype, for which there seems to be little to no evidence of a direct benefit.

One of the major claims of the PH Diet relating to athletes is that ingesting foods such as grains, dairy and milk alter calcium levels in the body due to their phosphate content and may affect bone health, increasing the likelihood of injuries such as stress fractures. 

However, a research paper reviewing 12 other studies in this area found that this was not the case stating Further, while its supporters claim that by consuming a more alkaline diet you make your body less acidic thereby reducing the risk of various diseases such as cancer, a report published in 2010 asserts   

This report continues ‘Finally, when asked to comment on this diet, Dr Kirsten Brandt, Senior lecturer at Newcastle University affirms that ‘leaving Dr Brant to label the diet as ‘’. This evidence clearly suggests that popular though it is, the PH/Alkaline diet offers no benefit to athletes or the general public and should therefore be largely excluded from any consideration as a dietary philosophy for swimmers.

These diets have gained popularity in the UK with the recent success of commercial weight loss companies such as Lighter Life and The Cambridge Diet. For those combining VLCDs with exercise as a way of losing weight, research exists to show that a 12 week programme on such a diet  However, this finding is in comparison to obese individuals and rather than those with a healthy body weight. Also, while long term effectiveness is difficult to establish as there are only a handful of follow-up studies, it appears that in general, between 26%-100%+ of body weight is regained and that to keep this figure low, some form of food reintroduction programme is crucial. This leads to the conclusion that VLCDs are simply not sustainable and do not produce the longer term lifestyle changes that other nutritional philosophies encourage.

Lastly, what seems to be clear, is that VLCDs are inappropriate as a day to day nutritional choice for non-obese individuals, as, despite being described as , these diets are deficient in both calories and nutrients and are therefore inappropriate for active individuals such as swimmers. Around a quarter of weight loss achieved on VLCDs will be lean muscle mass and this is likely to result in a reduction in training quality and recovery as well as an increased risk of injury. Finally, fluid and electrolyte loss – because of a change in insulin levels and also because of the way that fat is broken down for use as energy – may also be high, predisposing athletes to a loss of performance, dehydration and associated serious medical risks. 

… we will bring together all the best parts of the diets that we have looked at, highlighting core principles and giving easy to follow practical advice that will allow us to maximise our training and recovery as well as our lives in general.