A few years ago I fasted every other day for a month to try out a human version of an experiment involving rats, to see if doing so would improve my vision. Read full details and results.
While I did this I noticed it was harder to stick with the fast if I ate a lot of rice or pasta on the eating days – I’d get so hungry later. My dad was telling me about this South African professor Tim Noakes who says we should eat a very low carb diet (less than 50 grams or so for people who are “carb intolerant,” which many are.) more info here.
So, I tried it out, since one of his claims is that you don’t experience hunger after four hours of not eating, as a lot of people do on normal or “low fat” diets. My experience was so good I did some research into the whole “Low-Carb” diet and into why various diets may be more or less healthy.
A Case for the Low Carbohydrate Diet
This isn’t meant to prove the low carb diet “works.” I’m just trying to summarize the explainations and evidence as I understand it.
Turned out in my case a low carbohydrate diet completely worked to prevent serious hunger after going for a few days. I wasn’t even counting grams of carbs or anything. If you don’t eat any bread, rice or pasta and no sugar or potatos you’re pretty much covered. No processed foods like Pop Tarts or breakfast cereal either, obviously.
Noakes advocates eating a relatively high fat percentage in your diet, around sixtey percent of calories from fat. That said he advises fat should be good quality, animal products should be grass / naturally fed to reduce omega-6 fats. No seed oils like canola, sunflower.
Prof. Noakes claims if you go with the very low carb diet you typically won’t feel hungry enough to need to eat meals more than every twelve hours. Instead of hitting a wall where you’re hungry all of a sudden you just gradually get more hungry, so you can put off eating for a few hours if you need to.
I’ve found this to be completely true for me. It can take a few weeks to shed the cravings for sugar and bread-type products but once you’re through the transition sticking to the new diet feels pretty easy (for me anyhow.)
Those were the reasons I tried out this diet. It also helped me lose about twenty pounds.
Low Fat or Low Carb?
There is a debate betweenlow-carb vs. low-fat, but this isn’t the right way to think about it. Even proponents of low-fat diets (serious researchers, I mean) such as Colin Campbell don’t claim high fat causes heart disease – what they claim is that high fat diets which derive their fat from animal sources aren’t as healthy as diets deriving their fat content from vegetable sources of fat.
Furthermore, Campbell says a true low-fat diet could go as low as 10% calories from fat, whereas studies comparing low-carb to low fat consider 30% fat to be low-fat, and those “low -fat” diets set up against the low-carb diets contain loads of relatively refined carbohydrates rather than healthy whole plant foods. It seems saturated fat poses little added risk of heart disease (Campbell agrees with this,) but it also may not be necessary if you substitute whole plant based food.
In addition, plant based fats like olive oil have been shown to have a protective effect on cardiovascular disease and animal based fat has not.
There have been some large studies at the population level showing that more meat overall increases cancer rates so that’s another reason to go easy on animal products. But not all animal products are equal – it really depends on how they’re fed, and overall metabolic problems from excess carbohydrates probably greatly out-weigh risks from animal fat and protein in the short-term.
The actual claims from low-carb diet proponents, rather than “low fat is bad”, is that excessive carbs, – which typically make up a lot of a “low-fat” diet – cause disease. Even many less refined carbohydrate sources, beyond refined sugar, like potatos, grapes, bananas, brown rice etc in excess will cause insulin resistance and lead to obesity, diabetes and heart disease.
Additionally, a large class of dietary fat and cholesterol doesn’t effect blood cholesterol and in any case (most) cholesterol (except omega-6 fatty acid) doesn’t cause heart disease.(This is the claim) Instead, high LDL cholesterol may be a marker for insulin resistance.
Carbohydrates, Diabetes and Heart Disease
Cardiovascular diseases formerly believed to be caused by fat and cholesterol instead come from inflamation ultimately caused by insulin resistance and high blood sugar. Here’s a talk laying out the idea.
Even without proving the link with insulin directly there’s lots of evidence that high sugar in the diet is dangerous. Consuming refined sugar and carbohydrates increases inflamation and increases risks for disease: more information.
You can produce excess insulin because of insulin resistance which you get from constantly consuming a lot of carbohydrates your body has to neutralize with insulin, and gradually your body gets desensitized to the insulin, so your pancreas has to pump out more and more of it to signal cells to handle glucose. Here’s a more in depth explanation. Eventually your pancreas gets worn out and you get diabetes. Of course some people are much more likely to develop diabetes than others even when overweight – there’s a genetic component.
Calories in are not Calories Out
Obesity comes about because insulin removes glucose from the bloodstream – it’s trying to maintain a constant level – and the extra has to go somewhere. So injecting a large amount of sugar over a short time period is a problem. The liver stores energy from extra glucose as glycogen, but it has a limited capacity. Think of the liver as a buffer to keep blood glucose stable. Insulin also signals other cells to store glucose as fat. How Sugar Converts to Fat. Insulin causes cells to store fat converted from sugar
All this has good support both from known biochemistry and from observing people on different diets and is mostly non-controversial. The new thing some people like Tim Noakes are saying is that even what has been considered low carb (100 - 150 grams) isn’t low enough; that many people cannot tolerate even more than 50 grams per day on a regular basis; and if they exceed a threshold – different for every person – they will have problems.
That last point is critical to keep in mind. The fact that one person gains wweight on a particular diet and another doesn’t could come down to how “carbohydrate tolerant” their bodies are.
The big reason why low fat diets as practiced are not successful for people trying to lose weight or cut down on heart disease risk is that removing fat calories from the diet leaves room for sugar calories and flour, while making the low-fat food less satiating. Without a satiating fat in the low-fat versions of a food, to keep low-fat food products tasty,manufacturers need to add sugar. Check the nutrition information and you can see for yourself.
Unlike consuming high fat, low carbohydrate foods, eating high sugar and starch (high carb) foods causes a spike in insulin to restore blood sugar levels. This spike in turn drops your blood sugar level quickly and triggers a hunger response. So not only are you consuming food that’s immediately stored as fat if you have too much, you will get prompted a few hours later to consume more.
Alcohol and Low-Carb Diets
I looked up information on carb content in alcoholic drinks. Typical beers have like 15 grams. Maybe 8 on the low end and 25 on the high end. Wine goes from three to twelve grams a glass, basically dry wines have less and whites are lower. Hard alcohol is around 1 gram per serving.
Metabolizing alcohol will pre-empt metabolizing anything else so you’re going to have an effect if you drink every day – you’re delaying processing the other food by a few hours – but it’s not directly fattening or bad for you in moderation. Noakes says you shouldn’t drink every day if you’re trying to lose weight on the high fat diet.
What’s the Healthiest Diet?
As far as I can work out, diets in order of long term health:
- Whole Food Plant-Based (moderately low fat usually), some fish, , most fat from plant sources
- High fat, moderate protein allowing meat and dairy, while getting enough fiber and plant derived micronutrients. Downside is possibility of too much protein, not enough protective fats from plant sources.
- High carb, low fat vegitarian, plenty of fruit and veggies. Downside is possibility of consuming too much refined carbohydrates and starches.
- High refined carb, whatever else. You die sooner and suffer all manner of afflictions in the meantime. Almost guaranteed to consume more carbs than you can tolerate eventually.
- The carnivore diet. 100% meat. Yes it’s real. At first it may “cure” problems caused by a high carb diet, but very hard to get enough of essential vitamins, micro-nutrients and fiber. Will consume more protein than is probably advisable.
Background and Sources
A few important questions about the very low-carb high fat approach: Is this healthy for the long term? Is there a more healthy diet for long term, but this is the best for weight loss?
Some answers are in : this article
And, the upshot for why it works as a diet, from the above paper:
Several studies confirm that there is a spontaneous reduction in caloric intake when carbohydrate intake only is restricted to 5–10% of caloric intake (24).
In the most controlled study to date, an LCD led to hunger levels similar to those of a low-fat diet, even though the daily caloric intake with the LCD was 1000 kcal lower (13).
Another study used the Eating Inventory, a validated questionnaire assessing hunger and cognitive restraint, and found that hunger was reduced by 50% when measured after 1 wk of an LCD (25).
Another study examining a 20-g carbohydrate diet found that fasting serum leptin was reduced by 50% and fasting serum neuropeptide Y was reduced by 15%(26).
It may also be that the mere lowering of serum insulin concentrations, as is seen with LCDs, may lead to a reduction in appetite. In support of this idea, several studies have found that insulin increases food intake, that foods with high insulin responses are less satiating, and that suppression of insulinwith octreotide leads to weight loss (27- 29).