Better results from low carb than lower fat.

 There's a lot of chatter over the pond and on t'internet about a recent study comparing low carbohydrate diet advice with reduced fat.

The work was led by Drs Bazanno and Hu of Tulane University, New Orleans and funded by the US National Institutes of Health. Its stated objective was

to examine the long-term effects of a diet low in carbohydrates, as compared to one low in fat, on cardiovascular disease risk factors, including blood pressure (BP), body weight and composition, serum lipids, plasma glucose, insulin, adipocytokines (adiponectin, leptin, resistin), and C-reactive protein (CRP) among obese adults.

Fruit vs Fruit Juice

As a low carb person I eat berries and sometimes an apple, but fruit juice to me is just a sugar solution. Fruit itself seems to be universally regarded as A Good Thing (TM) and although Robert Lustig has said "the vehicle is irrelevant" when talking about fructose, and admits that he doesn't want to be the guy to say fruit is bad, the reliance on fibre as a moderator is somewhat optimistic.

Overfeeding and weight loss on oil

Over 40 years ago a paper presented two studies on overfeeding with a high fat diet. I was drawn to read this by wanting to see how it compared with Sam Feltham's experiments and to address the general question about overeating on a low carb diet.

The paper is by German authors - Kasper, Thiel and Ehl - and may have suffered a little in translation as the two separate studies are somewhat intertwined. Well, here goes -

All calories are not equal

I was recently drawn to read a report of a clinical trial of over-feeding, conducted by Bray et al of Pennington Biomedical Research Center. This was an inpatient study looking at the effect of protein on weight gain in people eating 40% more calories than required for maintenance of body weight.

This study was brought to my attention as evidence that the number of calories is more important than the composition of those calories, and it was said that "all the extra calories were from fat". On further examination I found that it actually shows something different.

Atkins and 5 / 7 a day

Bit off fuss in the news this morning where a new study (statistical analysis) suggests that 7 a day "portions" of "fruit and veg" is better than the currently recommended 5 a day based on general mortality as well as death from cancer, heart disease and stroke.

In other words if you eat more vegetables and fruit you're less likely to die in a car accident. This may seem flippant but a) it is April 1st and b) that's what they're saying when looking at "all cause mortality"....

Death risk from any cause decreased as fruit and veg consumption increased. Risk of death by any cause was reduced by:

14% by eating one to three portions of fruit or veg per day

29% for three to five

36% for five to seven

42% for seven or more

Fresh vegetables had the strongest protective effect, followed by salad and then fruit.

Fruit juice conferred no benefit, while canned fruit appeared to increase the risk of death - possibly because it is stored in sugary syrup, say the researchers.

Let's not forget that " Potatoes and cassava don't count because they mainly contribute starch to the diet " - not that low carb eaters would be bothering with those things anyway.

So where does this leave the health concious low carb eater ? The good old 42 year old fad that is the Atkins diet usually catches some stick on these occasions, but let's remind ourselves of the facts that in Phase 1, the most restrictive, the current Atkins plan requires 12 to 15 grams of carbohydrate from foundation vegetables.

So is the Atkins diet compatible with 5-a-day or 7-a-day of vegetables (and fruit) ?

According to conventional wisdom dietitians a portion is 80 grams which I think originates from the World Health Organisation. 5 or 7 a day at 80 grams each is 400 to 560 grams a day. If the carbohydrate content is low enough, less than 5 grams per 100 grams of veg, then the limits of Atkins Phase 1 are not incompatible with 5 or even 7 a day :-

	Grams / day of vegetables
Carbohydrate g/day	400	560
12	3.0	2.1
15	3.8	2.7
	Carbs g/100g

[ Note for Americans - UK / EU labelling reports carbohydrates separately to fibre, effectively "net carbs", so these numbers are lower than you are used to. ]

Some example vegetables from Tesco.com :-

	Carbs g/100g
Green beans	3.2
Brussel sprouts	4.1
Cauliflower	3.0
Savoy cabbage	4.1
Spinach	1.6
Kale	1.4
Mushroom	0.4
Romaine lettuce	1.7
Asparagus	2.0
Broccoli	1.8

Clearly it is possible to comply with 5-a-day of vegetables and 7-a-day too if you're careful to pick the right vegetables.  You may be able to add 80 grams of raspberries a day (3.7g of carbs) into your discretionary non-foundation veg carbs too, or as you move into Phase 2 the chocie of vegetables and berries will increase accordingly.

I conclude that the Atkins diet is entirely compatible with the "5 a day" message, in fact it's effectively built in with the 12-15g of carbs from foundation vegetables. Enjoy !


PS Full study behind the headlines is "Fruit and vegetable consumption and all-cause,
cancer and CVD mortality: analysis of Health Survey for England data" by
Oyinlola Oyebode, Vanessa Gordon-Dseagu, Alice Walker, Jennifer S Mindell.
To be found online, currently with Open Access.
JECH Online First, published on March 31, 2014 as 10.1136/jech-2013-203500


PPS You might be interested in an audio podcast about getting overweight children to eat more vegetables (and fruit).

Sugar

A lot of media fluster about sugar this morning, some single issue campaigning group trying to make out that a single substance or group of substances is behind the "obesity epidemic".

I'm sure these underemployed cardiologists have looked at the evidence, but the sugar consumption thing has always intrigued me as I used to make the stuff. In the UK we make / import about 2.5 million tonnes of sugar net of exports and it has been like this for 30 years or more. I must dig out those statistics.

Meanwhile I looked at a UK Govt food survey statistical digest and pulled out the data below :-

I have also been reading a paper from 1995 which observed that ..

The prevalence of clinical obesity in Britain has doubled in the past decade.....  However, average recorded energy intake in Britain has declined substantially as obesity rates have escalated.

So the fans of calorie restriction have a real problem. They can't blame obesity on gluttony, as several datasets and studies show that our calorie intake is declining. So they're left with sloth and assuming that we're all doing 1000 calories a day less activity (yeah, right) to justify the increase in obesity.

Likewise the fructophobic cardiologists, in remission from lipophobia, are going to struggle to explain the effect of declining sugar intake on increasing obesity.

Facts about Carbs

Last week the NHS published an opinion piece opposed to low carbohydrate diets. They didn't even get past the first paragraph before naming and attacking well known diet plans that have helped many lose weight. This is a shame, as we need to use any approach that works if we are to address the obesity issue, and carbohydrate restriction has been demonstrated to work in many studies :-

The above are all Randomised Control Trials, analysed with references at authoritynutrition.com and a similar list is at dietdoctor.com showing a large majority of studies finding higher fat / weight loss in the low carbohydrate group of the trial to be better than in the low fat group.

In the NHS article a single study of the Atkins diet is referenced and it is said that

 "A 2003 study found that a low-carb diet can produce quick results, but over the long term it does no better than a balanced diet featuring carbs."

The full story is a little more complex...

 "Subjects on the low-carbohydrate diet lost significantly more weight than the subjects on the conventional diet at 3 months (P=0.002) and 6 months (P=0.03)"

The weight loss at 12 months was still better in the low carb group, but high attrition rates and some issues with the trial design like mixing men and women reduced them below statistical significance (P=0.26). A picture is worth a thousand statistics :-

The attrition rate itself is also of interest -

"The percentage of subjects who had dropped out of the study at 3, 6, and 12 months was higher in the group following the conventional diet (30, 40, and 43 percent, respectively) than in the group following the low-carbohydrate diet (15, 27, and 39 percent, respectively)"

 so it appeared that the low carbohydrate diet did at least work better for more of its participants in that they were more likely to stick with it. carrying forward baseline data means putting the weight of dropouts at their entry value, which makes both groups look worse than the reality of those who completed the programme.

As we would expect there were improvements to blood lipid composition in the low carb diet of this study, but the NHS omit to mention this. Similar results appear across the studies linked to in the above reviews, and recent systematic reviews confirm the benefit of low carbohydrate eating in terms of reduced cardiovascular risk.

So, a shameful piece of conventional wisdom and anti-low carb thinking is published in a context that requires balance, integrity and accuracy. Those of us hoping for a Damascene conversion on the way to Stockholm are disappointed, and the Swedish review that concluded "too much carbohydrate, not fat, leads to obesity" was clearly a better piece of work than asking "Dietitian Sian" for her opinion.

Here are three facts omitted by the NHS :-

1. There are no essential carbohydrates that we have to eat in order to live. This is not the case for fats and proteins where we do need to take in some of each of them in food as our bodies can't make them.

2. There is no diagnosable disease of carbohydrate intake deficiency. Diabetes on the other hand is a difficulty in processing or controlling carbohydrates which leads to high blood sugar levels with clinical symptoms that can be serious. Excess carbs are stored as body fat once glycogen stores are full.

3. The human body at rest uses fats to provide about 2/3 of its energy requirements, with 1/3 from carbohydrates. At high / strenuous exercise rates the proportion of energy from carbs approaches 100%.

Carbs for energy are taken from food and from glycogen reserves which are limited to a maximum of about 2000 calories (kcal). There is only 5 grams of glucose in your bloodstream (20 calories, about 15 minutes worth at rest). A lean athletic man of 75 kg / 165 lbs / 11 st 11 lbs with 12% body fat has about 70000 calories of fat reserves, ideal for endurance activity or periods of famine.

In the absence of dietary carbohydrates the brain switches to ketones as a fuel and glucose is made by the liver - we are dual fuelled / hybrid powered beings where carbs provide short term power / acceleration and fats provide long term endurance and survival. The NHS articles assertion that we are 100% fuelled by glucose is incorrect. Carbohydrates are a low density fuel - would you rather haul fat at 9 calories per gram or carbs at 4 cal/g over the Antarctic ice sheet or up Everest ?


Have a Happy Christmas !