The High-Fat, Low-Carb Diet

There are countless types of diets trending today: weight loss, crash, detox, low-fat , high-fat, low-carb and many more! It seems like every time we turn on the TV or read the news, there’s another fad diet promising real results. People get excited and jump on the bandwagon only to discover that it’s too difficult to follow or doesn’t work with their lifestyle.

Recent research has confirmed the message that practitioners in holistic medicine and nutrition have been delivering for years: that eating more foods with healthy fats and less carbohydrates, as well as getting healthy portions of fruit and vegetables, can be good for your overall health and can help many people lose weight. Many people find it difficult to heed this advice however, since it sits in stark contrast to the message we’ve been receiving over the past 50 years that all but vilifies fat consumption.

The low-fat message of past decades had a downside: many people replaced fat with refined carbohydrates and sugars, which did not improve their health, and very low-fat diets can lower good cholesterol (HDL). But the type of fat matters. Saturated fat raises LDL (“bad”) cholesterol, and replacing saturated fat with unsaturated fats, such as those in olive oil, nuts, avocados and fish, lowers LDL and cardiovascular risk. That is why heart-health guidelines still advise limiting saturated fat. A lower-carbohydrate diet built mostly on unsaturated fats is one reasonable option within those limits.

How It Works

The science behind the concept of eating more fat and less carbohydrates is quite sound. You see, fat is very satiating, so you become fuller more quickly than you do with carbohydrates. Thus, while fat has more calories per gram than carbohydrates, you will actually end up eating less. Haven’t you ever noticed yourself mindlessly finishing an entire bag of chips before you realize what happened? That’s because you can eat a lot of carbohydrates before ever feeling ‘full’.

Further, carbohydrates are broken down into glucose and cause a release of insulin. The more carbohydrates we consume, the more insulin is released into the bloodstream. Insulin then causes a sudden drop in blood glucose levels, leading to cravings and the in infamous ‘sugar crash.’

Eventually, your cell receptors become less sensitive to the effects of insulin, which will cause your body to release more insulin, store more fat, and decrease your insulin sensitivity, ultimately this can lead to Type II Diabetes. However, as long as you avoid refined carbohydrates, you will eventually avoid the cravings for these unhealthy foods when you’re hungry (or especially when you aren’t).

Adaptation Phase

Of course, you won’t be able to switch your diet overnight and feel no effects. During the first week or so of drastically decreasing your carbohydrate intake, you will likely experience sugar withdrawal from the processed foods you have been consuming. Sugar triggers the release of opioids and dopamine in the brain’s reward system. In a review of animal studies, Dr. Nicole Avena and colleagues found that rats given intermittent sugar access showed some signs resembling dependence, although whether sugar is truly “addictive” in people is still debated. The lightheadedness and nausea some people feel early on are often due to the shift in fuel and to fluid and electrolyte changes (sometimes called the “keto flu”).

This detox period, or adaptation phase simply means that your body needs time to produce the enzymes and other chemicals required to start using fat as its primary fuel source. Throughout this period, it is common to experience symptoms, such as: brain fog, fatigue, headaches, lightheadedness, insomnia, bad breath, low-level dehydration, and a feeling of heaviness throughout your body.

For most people, the adaptation phase passes within the first week or two. Talk with your prescriber before starting if you take medication for diabetes (such as insulin, sulfonylureas or SGLT2 inhibitors), blood pressure medication, lithium or valproate: carb restriction can lower blood sugar quickly, SGLT2 inhibitors carry a risk of ketoacidosis, dehydration can raise lithium levels, and valproate needs special caution with ketogenic diets. People who are pregnant, underweight, or have a history of an eating disorder should not start a restrictive diet without medical supervision.

Benefits

A study by Dehghan and Mente found, in a large observational study, that very high carbohydrate intake was associated with a higher risk of mortality whereas higher total fat intake was associated with a lower mortality rate. Observational studies can’t prove cause and effect, but for many people a lower-carb diet may offer benefits such as:

• Possible improvements in weight, blood pressure and blood sugar
• Potential for fat loss and muscle gain
• Possible decrease in some inflammation markers
• Decreased cravings and appetite, preventing potential of overeating
• Improved triglycerides, HDL and blood glucose in many people (LDL can rise on versions high in saturated fat, so have it checked)
• Fewer blood-sugar swings for some people

What to Eat and What Not to Eat

An ideal meal plan following the high-fat, low-carb method would include approximately 50% percent of your calories from healthy fats, 25% from carbs, and 25% from protein. Don’t confuse healthy fats with trans fats and “fatty foods” however. Get most of your fats from unsaturated sources such as nuts, seeds, avocado, olive oil and wild oily fish (salmon, mackerel, sardines). Keep butter, coconut oil, fatty cheeses and fatty cuts of meat to smaller amounts, since they are high in saturated fat, and limit processed meats such as bacon. Poultry and whole eggs can round out your protein.

Don’t forget to fill up on cruciferous vegetables (broccoli, cauliflower, cabbage, Brussel sprouts), leafy greens (spinach, arugula, chard), asparagus, zucchini, cucumber, etc.; and, beware of overdoing it on vegetables high in carbohydrates, such as potatoes, sweet potatoes, corn, beets, and peas. In addition, Miller and Mente found that high fruit and vegetable intake is associated with lower risk of non-cardiovascular and total mortality. It is suggested that three to four servings of raw fruits and vegetables per day is an appropriate intake.

Remember to avoid low-fat, processed, sugary, refined products, as well as starchy carbohydrates like wheat, oatmeal and rice. Avoid fast foods, soda and alcohol. Focus instead on eating the freshest, closest-to-nature whole foods you can access. A good rule of thumb to follow is if it has a long expiry date, you’ll want to avoid it.

The best time to make a change is now. Once you make it through the adaptation phase, many people notice steadier energy, fewer cravings, progress toward a healthy weight, and fewer sugar crashes. Talk with your clinician about whether this approach fits your health and medications.