Low carb diets 'cut heart energy'


Scientists have found high fat, low carbohydrate diets can reduce energy to the heart.

The Oxford University team say it is unclear at this stage whether this could have a damaging impact on health - but say more research is needed.

Many people have lost weight quickly by following such diets - but scientists fear they may not be good for health in the longer term.

The new study is being presented to an American Heart Association meeting.

The Oxford team monitored 19 people over a two week period.


They found that the energy stored in the heart was reduced by an average of 16% among those who followed a high fat, low carbohydrate diet.

In some people the energy reduction was as much as a third.

Their hearts also became slightly 'stiffer' - not relaxing quite as well as before the diet.

One of the participants even noticed he could not manage his daily run while on the diet.

The changes were reversed within two weeks after returning to a normal diet.

Lead researcher Professor Kieran Clarke told BBC News that people with illnesses such as diabetes, obesity and heart disease also had lower than normal heart energy levels.

A more severe form of energy depletion is one of the features of heart failure, where patients struggle with physical exertion because they have little 'in the tank'.

Professor Clarke said further research should be carried out on a larger sample over a longer period.

"Our study gives us some interesting insights into how extreme diets might be affecting us.

"Of course, this is a small and short-term piece of work. The body is remarkably adaptive and what we don't know is whether our hearts would have gradually returned to normal had we stuck to the diet long-term."

The British Heart Foundation, which funded the work, said the results reinforced their view that people should not follow high fat, low carb diets to lose weight.

Professor Peter Weissberg, BHF medical director, said: "Diet devotees can be reassured that this research in no way suggests that the high fat-low carb regime is going to give them heart failure.

"However, they should be aware that such unbalanced diets are a major insult on their bodies' metabolism and, as this study shows, may be having direct effects on their hearts, particularly since they tend to be high in saturated fat.

"We would certainly not recommend high fat-low carb diets to anyone who wants to lose weight and look after their heart.

"Achieving this with a balanced diet and regular exercise is sustainable for life and, for most people, is the safest way for your heart."

http://news.bbc.co.uk/1/hi/health/4435046.stm

Snort. I have more energy than I ever had eating low carb, high fat. I am not a scientist, but 19 people over two weeks doesn't sound like enough of a sample to have any meaning at all. The fact that Professor Clarke called low carb an "extreme" diet kind of dials us in on his predisposition on the topic.


Then basically Clarke had no conclusion to offer, but decided to offer one anyway.

When I visited my doctor last week for a routine check-up, he was awed by my excellent lipid profile, healthy weight (sustained over time) and very fit condition, owing to regular cardio and resistance training.

He commented that some of his very overweight patients have a hard time with exercise when they first begin a low-carb routine. Since I began low-carb (three years ago) with a good base of muscular and cardiovascular conditioning, I've been able to handle it quite easily.

These studies may very well involve fat, unfit people.

For anyone who is completely out of shape, I would suggest taking things slowly. By-the-book low-carb program. Light to very moderate exercise at the beginning. The heart is a muscle, after all. You wouldn't (couldn't!) start your flabby biceps on 25-lb dumbbells, so don't try the equivalent with your heart.

My thoughts exactly!

I've been on Atkins almost a year now and I just had a stress echo done a few weeks ago. I've been experiencing PVCs (premature ventricular contractions) due to thyroid issues. As my medication's been tweaked these have been greatly relived, but at the time they were freaking me out badly.

Anyway, the Dr. was amazed at how well I did on the treadmill. He said he couldn't do any better himself (he's very fit, I'm still a very fat 42 year old) and said my heart shows it's very athletic and healthy. I don't have the exact percentages on everything from the stress echo, but they were very good and went a long way to reassure me I was in no immediate danger of dropping dead.

2 weeks does not measure the health effects of low-carbing, it will only measures the sugar withdrawl symptoms.

It's very much like taking measurements of a junky soon after they've gone cold turky, and saying "based on our 2 weeks reearch, it is unhealthy to get people off crack, due to health concerns we observed after taking them the drugs ..."

Wa'il

The BHF made sure that the study they financed was designed to prove their prejudices were justified.

The first two weeks after eliminating most carbs from the diet is the time when the body is increasing the enzymes/hormones necessary to use more fat as an energy source. It has been burning mostly glucose (carbs) and needs time to adapt. Of course you will have less energy during this time. The researchers had to have known that and purposely picked two weeks to make sure that low-carbing looked unhealthy. If they had done six weeks, the results would have been much different.

For example in this analysis of low-carbing and exercise, an adaption time is found to be necessary.
After an adjustment period, I found that I can exercise at higher heart rates for longer periods of time on low-carbs than when I was chugging down carbs by the mouthful. My performance has significantly increased for my bicycling.

Same here. All my life, I never "got" exercise. People said how good it made them feel. I'd work out, and wouldn't have energy for a couple of days following. It never seemed to do any good, and almost always made me feel poorly. I didn't show improvement, even when I was a lot younger and smaller. I ran nearly every day one summer, and never really improved my performance, always felt lousy during and after. I couldn't sustain that.

Flash forward to this year. I can bike a solid hour without stopping and feel absolutely great during and after. It's like coming in from the cold. This is what it's supposed to be like, what they were always telling me exercise was supposed to be like.

This study is obviously designed to prove what they wanted it to prove.

I'd say that this was astonishingly bad science, being used to draw conclusions almost out of thin air. It is well-known that there are various transient effects when one changes from a standard high-carb diet to a low-carb, ketone-burning diet. Some people do seem to experience fatigue. And some don't.

But the body is designed to function burning fat. Some of us claim that fat burning is actually the primary mode and that burning carbs is the backup, but whether this is true or not, burning fat is *normal*. Even if it is not common under current conditions, with aisle after aisle of high-carb processed foods in the supermarkets.

You know, when I've been off carbs for a while, and I eat something with sugar in it, I feel buzzed, it's pretty unpleasant, worse than too much coffee. Does this prove that sugar is bad for me?

Maybe. But I wouldn't dream of offering that as scientific proof!



Fifty years from now, these people are going to look like complete idiots. They already look that way to anyone who has seen through the low-fat dogma, the total lack of scientific rigor behind all these dietary recommendations.

A "high-fat, low-carb" diet is generally successful for weight loss, if one is overweight when starting the diet. And such diets seem to also improve blood lipid numbers (especially increasing HDL cholesterol and lowering triglycerides). So *why* wouldn't this "expert" recommend such a diet? Because someone saidm "I can't go on my run today"?

Sheesh.

I hear people with cancer also get sick as in vomiting alot, therefore any time we vomit it must automatically be cancer!

I'm sorry if that bit of sarcasim offended anyone. I am just pointing out how silly that bit sounds in the article. It's like the olden days when the fever was the enemy because that was what people could see, not the causes of the fever.

i disagree in that i think almost completely cutting out any one calorie containing nutrient is extreme by definition. be that fat or carbs. i do it, but i still can see it considered "extreme."

I just read Life Without Bread, and the authors of that book state that the heart's preferred energy source is fat. Lemme find a quote or reference or something:

"One of the body's best-kept secrets is that the heart uses fatty acids exclusively for energy, and these are saturated fat ... how can people say that most healthy foods for the heart are low in fat, when the heart muscle is known to require fat in order to beat?"

Their sources for this information were:
Lawson, L.D. and F. Kummerow. Lipids 14 (1979): 501-503.
Garg, M.L. Lipids 24 (1989): 334-339.

It amazes me how ill-conceived these "studies" are that promote low-fat and how (willfully?) ignorant most folks are about this topic.

Oh how we should stand in awe and bask in the light of yet another wonderful announcement of a medical breakthrough in dietary science--that is, low-carb diets are bad for your heart.

How can we refute such solid evidence? After all, it was performed by human beings, who are without prejudice, without presupposition, with pure motive, totally objective, uninfluenced by money or power or bias, devoted to the pursuit of pure truth regardless of the outcome or consequence, and never prone to error or misinterpretation.

We should be ashamed of ourselves for every questioning yet another brilliant study, performed brilliantly by brilliant people. Bravo, I say.

NO carb is extreme, VERY LOW carb is extreme if continued long, perhaps. But what a "balance" is, is less than clear.

Low fat is probably extreme. Low carb (i.e., under, say, 100 grams per day) may well not be. Atkins induction (20 grams per day) might be considered extreme, but only if the diet is not arranged so that necessary nutrients are included.

The fact is that carbohydrates, per se, are not necessary for human nutrition. You can eliminate them almost entirely from the diet and it is not clear that this will cause any harm at all. (But if you get rid of all the fiber, if you are missing vitamins because you avoid vegetables that might have some carbs but also other important nutrients, then, yes, harm is more possible, but it is not the carbs themselves which are necessary.)

Eliminate all fat from the diet, you get sick, it appears. Likewise protein.

The point, really, is that low fat deserves the epithet "extreme" more than low carb. What is considered low carb is not really that low. Indeed, we could properly say that the Food Pyramid is an extremely high-carb diet, though, certainly, one can eat a lot more than the Pyramid recommends.

my exact thoughts... you beat me to it!