Fat Versus Carbs — Higher Amounts of Dietary Fat Actually Improve Your Metabolic Health

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By Dr. Mercola

Most of us eat too much sugar, and far too little healthy fat. Many also eat too much protein, which may actually be even riskier than a high-carb diet in some health respects. Unfortunately, the notion that glucose is the preferred fuel for your body has become deeply ingrained over the decades.

This misguided advice has been a driving force in our obesity, diabetes, heart disease and cancer epidemics, in large part because low-fat, high-carb diets prevent healthy mitochondrial function. Dietary fats are actually the preferred fuel of human metabolism. The benefits of a high-fat diet are investigated in the BBC documentary, “Fat [Versus] Carbs With Jamie Owen,”1 which originally aired in October, 2016.

In it, Owen, a Welch journalist and BBC news anchor, challenges conventional diet advice by going on a low-carb, high-fat diet (LCHF). This is also the focus of my latest book, “Fat for Fuel,” which is by far the most important book I’ve ever written. Shipments of “Fat for Fuel” will begin on May 16, leaving you just a couple more days to reserving your copy, which will entitle you to six free bonuses.

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Fat Versus Carbs

In 2015, Owen tested out more traditional weight loss advice, cutting sugar and exercising more. He did lose weight as a result. Alas, it wasn’t long before he’d put it all back on — and then some. This is a notoriously common issue. As noted by Owen, Wales has a major obesity problem, as do many other nations, including the U.S., and most are not overweight for lack of desire or effort to slim down.

Their food choices are simply preventing them from achieving their goals, and conventional weight loss advice is wrong on key points that further prevent long-term success, even if you follow it to the letter. Counting calories, eating low-fat fare and exercising more is not the answer. If it were, two-thirds of the American population would not be overweight, and half would not have pre-diabetes, diabetes or other chronic illness.

Last year, the British National Obesity Forum (NOF) and the Public Health Collaboration (PHC) issued a joint report on obesity based on the analysis of 43 studies, warning the policy to encourage people to eat a low-fat diet is having a “disastrous impact on health.”2,3,4

Current Dietary Guidelines Are Fundamentally Flawed

Owen interviews Samuel Feltham, a master personal trainer, director of the PHC5 and one of the authors of this controversial report, which calls for a complete overhaul of the official dietary guidelines in the U.K. According to the authors, the current guidelines (which promote low-fat, high-carb diets) have been manipulated and corrupted for commercial gain by the food and beverage industries, and are based on flawed science.

In conclusion, the report suggests a LCHF diet — and cutting out between-meal snacks — may be the real answer to the obesity epidemic. As noted by NOF chairman David Haslam:6

“As a clinician treating patients all day every day, I quickly realized that guidelines from on high suggesting high carbohydrate, low-fat diets were the universal panacea, were deeply flawed. Current efforts have failed, the proof being that obesity levels are higher than they have ever been, and show no chance of reducing despite the best efforts of government and scientists.”

Key Findings

Some of the key findings of the NOF/PHC report include the following:

Eating fat does not make you fat. Studies show high-fat, low net-carb diets are in fact superior to low-fat, high net-carb diets for weight loss

Saturated fat does not cause heart disease; in fact, it’s good for your heart. There’s no evidence to suggest avoiding saturated fat or dietary cholesterol reduces heart disease or death from heart disease. A recently published reanalysis of evidence from 40 years ago also does not support restricting saturated fat to protect heart health.7,8,9,10,11,12,13, 14

One of the original researchers involved in this study was Ancel Keys — the man who initially proposed the link between saturated fat and heart disease — and it’s believed he was largely responsible for suppressing these damning findings, as they don’t support his original hypothesis.

Only parts of the trial’s results were ever published, leaving out the key finding that replacing saturated fats with vegetable oil had no benefit on mortality. While vegetable oils did lower total cholesterol levels by 14 percent after one year, overall mortality risk actually increased.

For every 30-point drop in total cholesterol there was a 22 percent increased chance of death. The vegetable oil also did not result in fewer cases of atherosclerosis or heart attacks. On the contrary, autopsies revealed that while both groups had similar levels of arterial plaque, 41 percent of the vegetable oil group showed signs of at least one heart attack compared to just 22 percent of those in the saturated fat group

To lose weight, stop counting calories and reduce meal frequency. Calories are not created equal. They have differing metabolic effects depending on their source, so counting calories is useless for successful weight loss.

That said, excessive snacking is a significant contributing factor to obesity. To lose weight, the report concluded you need to reduce your meal frequency. I recommend limiting it to two meals per day, either breakfast/lunch or lunch/dinner, within a six- to eight-hour window each day. It’s also beneficial to avoid eating at least three hours before bedtime to protect your mitochondrial function

You cannot outrun a poor diet. Obesity cannot be conquered simply by increasing exercise, as obesity is rooted in metabolic dysfunction that leads to abnormal energy partitioning

High-Fat Diet Actually Improves Your Metabolic Health

While your body can use and needs both carbs and fat for fuel, they’re not equal in terms of value and benefits. Fat is in fact a far preferable fuel for your body.

When your body is able to burn fat for fuel, your liver creates water-soluble fats called ketones that burn far more efficiently than carbs, thus creating far less reactive oxygen species and secondary free radicals that can damage your cellular and mitochondrial cell membranes, proteins and DNA.

Ketones also mimic the life span extending properties of calorie restriction15 (fasting), which includes improved glucose metabolism and reduced inflammation. They also decrease inflammation as they are HDAC (histone deacetylase) inhibitors. Part of the problem with a high-carb diet is that when your body burns glucose as its primary fuel, it inhibits your body’s ability to access and burn body fat.

With an ever-present supply of carbs, your liver downregulates the entire fat burning process. When both fat and carbs are available, your body will also use the carbs for fuel first. Diets high in refined fructose are particularly troublesome, as fructose activates the enzyme fructokinase, which in turn activates another enzyme that causes cells to accumulate fat.

Rarely if ever skipping a meal is yet another factor that prompts your body to keep burning sugar as its primary fuel, which down-regulates enzymes that utilize and burn stored fat. When you intermittently fast, your liver will run out of glycogen, forcing it to use glycogen stored in your fat cells instead.

As you can probably tell by now, all of these processes help explain why it’s so difficult to shed weight while you’re still eating lots of carbs, especially if you’re eating several times a day — even if you’re getting plenty of exercise. Fortunately, the answer to this conundrum is simple. To get out of this metabolically unhealthy loop and rev up your body’s fat burning engine, you need to eat more healthy fats, limit net carbs and, ideally, skip a meal here and there.

Healthy Fats 101

To effectively burn body fat, you may need as much as 50 to 85 percent of your daily calories to come from beneficial monosaturated and saturated fats, which include the following:

Olives and Olive oil (make sure it’s third party certified, as 80 percent of olive oils are adulterated with vegetable oils. Also avoid cooking with olive oil. Use it cold)

Coconuts and coconut oil (excellent for cooking as it can withstand higher temperatures without oxidizing)

Butter made from raw grass fed organic milk

Raw nuts, such as macadamia and pecans

Seeds like black sesame, cumin, pumpkin and hemp seeds


Grass fed meats

Lard and tallow (excellent for cooking)

Ghee (clarified butter)

Raw cacao butter

Organic pastured egg yolks

Animal-based omega-3 fat such as krill oil and small fatty fish like sardines and anchovies

As noted in the documentary, and as you can tell from the list above, any fat found naturally in food — whether animal- or plant-based — is healthy for you. Far from being an artery-clogging health disaster, saturated fat found in animal products and coconut oil:

  • Increases your large fluffy LDL particles, which are not associated with an increased risk of heart disease
  • Increases your HDL levels, which is associated with lower heart disease risk. This also compensates for any increase in LDL
  • Does not cause heart disease, as made clear in a large number of studies16,17,18,19,20,21
  • Serves as a “clean-burning fuel” for your brain and mitochondria, producing far less damaging free radicals than sugars and non-fiber carbs

Harmful Fats 101

For all its flaws, Keys’ hypothesis that fat promoted heart disease was not entirely incorrect. He just wasn’t specific enough. The problematic fats are all manmade. Harmful fats that contribute to heart disease are trans fats and highly refined polyunsaturated vegetable oils.22

The former acts as a pro-oxidant, whereas the latter are high in damaged omega-6 and produce toxic oxidation products like cyclic aldehydes when heated. Vegetable oils promote oxidized cholesterol, which becomes destructive when entering your LDL particles.

Additionally, omega-6 polyunsaturated fats, when taken in large amounts, cannot be burned for fuel. Instead, they’re incorporated into cellular and mitochondrial membranes. Here, they become highly susceptible to oxidative damage, which ultimately damages your metabolic machinery.

In her book, “Deep Nutrition: Why Your Genes Need Traditional Food,”23 Dr. Cate Shanahan explains these and other harmful effects of processed vegetable oils. Of particular note is their effect on your brain and gut.

In summary, these oils promote gut inflammation, disrupt blood flow through the arteries in your brain, deplete your brain of antioxidants, attack the nerve cellular architecture and impair brain development through mutagenic effects on DNA and altered epigenetic expression.

Vegetable oils made from genetically engineered crops have additional health risks, thanks to the presence of toxic herbicide residues like Roundup.

Real-World Effects of an LCHF Diet

Owen lost 7 pounds (0.5 stone) in just seven days on the LCHF diet. At the end of three weeks, he’d lost just over 13 pounds (6 kilos), but weight loss is far from the only benefit. As noted in the documentary, it can also help manage or reverse diabetes, improve your energy level and mental clarity.

The scientific evidence also strongly suggests it can help prevent many common chronic diseases, including cancer and heart disease. While total cholesterol by itself is a virtually useless parameter by which to gauge your heart disease risk, Owen’s total cholesterol, which was slightly elevated at 5.6 nmol/L (216.15 mg/dL24) at the beginning of the experiment, went down to 4.9 nmol/L (189.13 mg/dL).

This result came as a great surprise to his doctor, who initially had warned him to go easy on the fats and restricted his experiment to three weeks, in fear of what it might do to his arteries. As it turns out, his cholesterol actually improved on the high fat diet.

“This low-carb, high-fat diet may not be for everyone, but it seems to have worked for me,” Owen says. “I’ve lost the best part of a stone [14 pounds], my cholesterol has dropped, and I feel pretty good. The one thing I’ve taken from all of this is to be more aware of the food that I eat …

[T]he reality is I still have a lot of weigh to lose, and so does the majority of the population in Wales. We eat too much; we eat the wrong things, but confusing contradictory dietary advice is a serious, [contributing] factor to our big fat problem, and that is serious food for thought.”

LCHF Diet Helps Solve Many Health Problems

As evidenced in the documentary, many conventional doctors and dieticians are still leery of high-fat, low net-carb diets, claiming a lack of long-term health outcomes prevents them from supporting such a regimen. Little is said about the fact that overwhelming data demonstrates the long-term health outcomes of current dietary recommendations are an absolute disaster.

You can hardly do any worse than following current guidelines. Having delved deep into the medical literature in preparation for my book, “Fat for Fuel,” I believe a diet high in healthy fats with low net carbs and moderate amounts of protein is the key many have been looking for, as it solves more than one problem.

Not only does it help you shed excess body fat, it does so while improving metabolism, boosting overall energy levels, lowering inflammation, promoting optimal health and maximizing longevity in a number of different ways. As a general guideline, to optimize your fat-burning system:

  • Limit your net carbs (total carbs minus fiber) to a maximum of 30 to 40 grams per day. You can consume as many high-fiber veggies as you like. They’re carbs, but since they’re high in fiber, they’re typically quite low in net carbs
  • Limit protein to a maximum of 1 gram of protein per kilogram of lean body mass
  • Increase healthy fats to 50 percent to 85 percent of your daily calories

Intermittent fasting will facilitate and speed up the process. Once your fat-burning ability has returned, (assuming you’re still eating right), you only need to intermittently fast on a maintenance basis.

Source:: Mercola Health Articles