My Day on a Plate: Evelyn Stevenson

An article popped up on BBC Health this week that caught our eye at The Foundry.

http://www.bbc.co.uk/news/health-14882832

It seems that those in the world of dietetics are finally realising that some of their advice may not be all it is cracked up to be. This is interesting given the amount of criticism ‘nutritionists’ have come in for over recent years for recommending such ‘radical’ approaches as reducing carbohydrate intake for weight loss or the suggestion that dietary fat may not actually be responsible for heart disease. The fact is that little in this article is of news to those of us who have been working on transforming body composition for many years now.

Is it really as simple as that?

For a long time now those in the seats of nutritional policy power have reinforced that to lose weight you simply have to create a calorie deficit of 500 calories a day and bingo, weight falls off, in a rather conveniently measurable 3500 calories (or the amount of energy in a pound of fat) a week.

Well of course, the real world tells us that it isn’t quite that simple and it seems that the British Dietetic Association may be starting to agree. Amusingly the article quotes Helen Bond from the BDA who says that “we recommend it, it’s what we are taught. But I don’t know what the scientific evidence for it is”. Well, score one for nutritionists vs. dieticians there. I can’t help but think that Ms Bond will cringe when she sees that quote in print, although I applaud her candid response. It seems that experience and instinct can precede scientific guidance after all. However, I cannot help but wonder how many more ‘established scientific guidelines’ currently trumpeted are as thinly supported by any actual evidence?

Do I need to include the chocolate brownie? I know I shouldn't have but it was my boss's birthday...

The fact is that studying diets is in itself is very difficult and any research needs to be carefully considered before applying it to the entire population. Drop out rates tend to be extremely high, in fact often 50% or more, skewing results to show the diet in question to be far more favourable than is actually the case. However, these drop out rates should tell us something; that many people lack the ability to stick the course at a diet, for a multitude of reasons. Diet studies tend to also rely on a hefty amount of self-reporting and subject adherence, another major problem. Housing and feeding large cohorts for a meaningful period of time is simply not achievable and any study that is reliant on self-reported data needs to be taken with a hefty pinch of salt (which is another topic where advice and evidence aren’t always congruent). Participants clearly over-estimate their activity levels and underestimate (or simply lie) about their food intake.

Of course, similar problems have been encountered when studying the effects of exercise on weight loss. Food intake is rarely controlled, drop out rates are high and, even when they aren’t, the ability of subjects to complete or maintain a meaningful intervention often makes for dismal reading. This has lead to many drawing erroneous and misleading conclusions that aren’t actually supported by the research, such as “exercise will make you fat” or other similar headline grabbing, but incorrect, statements.

Professor John Blundell (a brilliant but seemingly unknown researcher to those fitness experts who would write these assertions) has clearly demonstrated that, as with nutrition, the response to and effectiveness of exercise is highly individual. For an in depth and highly comprehensive review of the science of this area I’d highly recommend this paper: http://www.portalsaudebrasil.com/artigospsb/obes051.pdf. Those who tritely state that exercise doesn’t work for weight loss as it makes you eat more food would do well to read this and prepare to reconsider your viewpoint. For those of you who like to write these sort of statements without actually reading any kind of evidence I will quote directly and even bold the good bit for you:

“Physical activity has the potential to modulate appetite control by improving the sensitivity of the physiological satiety signalling system, by adjusting macronutrient preferences or food choices and by altering the hedonic response to food. There is evidence for all these actions. Concerning the impact of physical activity on energy balance, there exists a belief that physical activity drives up hunger and increases food intake, thereby rendering it futile as a method of weight control. There is, however, no evidence for such an immediate or automatic effect. Short (1–2 d)-term and medium (7–16 d)-term studies demonstrate that men and women can tolerate substantial negative energy balances of  ≤ 4 MJ energy cost/d when performing physical activity programmes.”

The article continues to discuss a new computer model of predicting weight loss from a Dr Kevin Hall, who for a PhD gives a rather loose summary of the paper saying “we tested it on about 100 people and it gave a good fit. It was pretty accurate”. Well I don’t know about you but with such precise and specific evidence like that I’m convinced. Or maybe not, as the author infers from this that weight loss will be identical in the short-term regardless of whether you cut dietary fat or carbohydrates.

So, we are right back to square one it seems and it is just about the calories?

Well, not exactly, as the preponderance of evidence would certainly not suggest that weight loss is the same on a low-fat or low-carbohydrate diet, in particular if you are insulin resistant. In fact several studies have found significant differences in weight loss when considered in relation to insulin resistance and carbohydrate/fat intake. This is an aside to altering protein levels, which has also been shown to have significant impact on body composition change, with higher protein levels proving more effective for weight loss. Of course, as we have established everyone reacts differently to diets, but my advice remains the same for the obese individual:

1. Begin to reduce carbohydrate intake, in particular refined and processed carbs such as pasta, bread, juice etc.

2. Begin to raise protein intake, eating some with each meal.

3. Start to exercise at a level that is sustainable, enjoyable, and achievable. This allows for progression, which can be highly motivating.

4. Increase daily non-exercise activity (believe it or not, many will reduce this when they start exercising, thereby nullifying many of the beneficial effects).

For now though, take solace as in the words of beardy counsellor Robin Williams: “It’s not your fault, it’s not your fault”. The powers that be have been lying to you.

Instead of focusing solely on managing your caloric intake you would do well to first work on managing your expectations of weight loss to avoid disappointment and despondency when things don’t happen quite as easily as many established ‘guidelines’ would have you believe. Hardened devotion to calories in vs. calories out seems the path to neurosis, obsessive behaviour patterns, and unrealistic expectations of weight loss and in turn a failure to maintain a successful diet approach.

As I have often said, the best diet is the one that you will actually keep to. While you are at it, most of you can stop worrying about your salt and your cholesterol too, but that really is another story.