An open-minded dietitian’s thoughts on the keto diet
Word on the street is that everyone and their mother is on the keto diet. But should you jump the bandwagon and follow it too?
High fat, moderate protein, low carbohydrate – it’s the basic constructs of the ketogenic diet. But keto isn’t just any low carb diet – it’s very low in carbs and really high in fat, more so than other diets like Atkins and Paleo.
With up to 80% of your daily calories coming from fat, this diet starkly contrasts not only other low carb diets but the Dietary Guidelines for Americans, which recommends 20-30% of daily calories from fat.
So what’s the deal? Is it safe? Are there benefits? Let’s take a deeper dive into this mainstream dietary trend, and we’ll give you our open-minded thoughts on whether this is diet has any merit.
How It Works: Ketosis
A keto diet restricts carbs, our body’s primary source of energy, to force the body into burning fat for fuel; a process known as ketosis. The extent to which carbs are restricted varies. On a classic keto diet, you’re looking at 5 – 10 % of calories from carbs per day; that’s about 20 – 45 grams of carbohydrate on an 1,800 calorie per day diet.
Meanwhile, you’re also moderating your protein intake. You want some protein to help preserve lean muscle mass, but you don’t want too much, or the body could begin converting it into energy – at least that’s how it works for a true ketogenic diet.
It takes about 3-5 days of carbohydrate restriction for the body to burn through its glycogen reserves (stored carbohydrate) and enter into ketosis. Rest assured, this mild dietary ketosis is not the same thing as the life-threatening condition, ketoacidosis.
Ketoacidosis occurs when ketone bodies accumulate to dangerously high levels and alter blood pH; it occurs primarily in people with insulin-dependent diabetes (insulin helps regulate ketone levels in the blood).* In order to stay in a dietary ketosis, you have to continue to restrict carbs; too much, even if it’s just at one meal, can cause your body to switch back to using carbs as fuel.
Want more on carbs? Check out our article. Top 7 Carb Myths Debunked.
Nutritional Breakdown of the Keto Diet
On a classic ketogenic diet you’re consuming 70-80% of your daily calories from fat, 20-25% from protein, and just a mere 5-10% from carbs, but there are many variations of the keto diet, most of which are more liberal in protein and lower in fat. Most of our keto-crazed friends and family members are doing a modified version similar to Atkins with a ratio of about 10% carbohydrates, 30% protein, and 60% fat. No matter the variation, here’s what holds true:
- Eat very little carbs
- Take in some protein
- Up your fat intake (a lot)
Keto-friendly Food Guidelines
Again, you’re going to see variation. What one keto cookbook touts may differ from what your next door neighbor tells you they’re doing, but here are a few general guidelines:
- Lots of fat & non-starchy vegetables: Think butter, lard, avocado, coconut (oil, meat, milk), nuts, seeds, and plant oils (olive, palm, coconut) for fat and leafy greens, cauliflower, broccoli, asparagus, bell peppers, mushroom, summer squash, and cucumbers for veggies.
- Some dairy: Certain dairy foods, like cow’s milk and sweetened yogurt, are high in carb and thus, avoided, but those that are naturally low in lactose (milk sugar) may be acceptable, namely cheese, butter, and unsweetened nut milks.
- Moderate protein: oily fish, free-range poultry, and grass-fed beef are often recommended for their omega-3 fatty acid profile, but pork, bacon, eggs, tofu, nuts and seeds also fit the bill.
- No Grains, Starchy Veggies, or Legumes: They’re too high in carbs. That means no pasta, cereal, bread, rice, potatoes, winter squash, beans or lentils.
- No fruit: At least on a strict version of the diet. Modified versions may allow certain fruits, like berries, in small portions.
- Little to no alcohol: On strict versions, alcohol is likely out but modified versions may allow some hard liquors and low carbohydrate wine and beer.
Potential Benefits of the Keto Diet
The keto diet began as a treatment for epilepsy in children back in the 1920s. Since then it’s been used for glycemic control and diabetes management, weight loss, increased energy, a metabolism boost –a combination of scientific and clinical applications to much less substantiated benefits.
Keto for Weight Loss
Currently trending: keto for weight loss and yes, it’s a thing and studies show it’s effective, at least in the short-term. As with any diet, if you reduce your calorie intake below your body’s daily needs, you’ll lose weight.
On a ketogenic diet designed for weight loss, you’re coupling calorie reduction with ketosis, and the benefits of ketosis start right away. As your burn through your glycogen stores and enter into ketosis, there is a natural diuretic effect. Your body releases water and you start losing weight (albeit, water weight) fairly quickly.
Seeing the scale drop quickly in those first few days can have a powerful effect on our motivation. Though we may feel tired, hungry, and irritable as our body adjusts to the change in diet, we’re compelled to continue on because we are seeing results.
Once in ketosis, most people report having reduced cravings and hunger, plus increased energy. The reason for this is likely multifactorial. It may be a result of the ketone bodies themselves, the satiety effect of protein, or improved insulin sensitivity and stabilized blood sugar levels.
It could also be due to a change in appetite control hormones, specifically a reduced output of ghrelin (the hunger hormone). No matter the reason, the side effects of ketosis make calorie restriction easier and thus, weight loss more successful.
And let’s not forget that when you eliminate certain food groups from the diet, you reduce variety, and that in and of itself can be helpful for people trying to lose weight.
The catch: While weight loss may be greater in the short-term, it seems to even out over the long-term when compared to higher-carb diets, and some people find that following a restrictive low-carb diet is not sustainable, which means you are susceptible to weight creeping back over time.
Keto for Glycemic Control
Controlling your carbohydrate intake and including protein and fat at every meal is going to help stabilize your blood sugar levels, and improved insulin sensitivity and lower hemoglobin A1c have also been noted in some studies that looked at the effects of a keto diet in people with type 2 diabetes.
The reality, however, is that it is unclear what the long-term effects are, especially in people who have diabetes in conjunction with other chronic diseases, like heart disease.
Keto for Heart Health
This one’s controversial, no doubt. Given the high-fat makeup of the keto diet, many people argue that there could be negative long-term health effects on cardiovascular health. The concern is primarily centered on saturated fat, which most leading authorities like the American Heart Association, recommends limiting to 5-6% of calories per day.
While some proponents of the keto diet promote saturated fats, like coconut oil and butter, it is possible to choose heart-healthy fats (e.g., mono- and polyunsaturated fats like avocado, olive oil, nuts, seeds, and fish) while on the diet and for now, that may be our best bet. According to the National Lipid Association Nutrition and Lifestyle Task Force, the evidence shows mixed results on LDL (i.e., “bad”) cholesterol levels with some studies showing an increase while on a keto diet.
Further, there is no clear evidence to support any positive effects on other cardiometabolic risk factors. Read more here.
There are certainly many other purported health benefits of a keto diet not covered here, but the message for most remains the same – there’s simply not enough evidence to support those benefits, at least not yet.
- Nutrient Deficiencies & Low Fiber: Whenever you eliminate food groups and limit variety in the diet, you increase your risk for nutrient deficiencies. As it pertains to keto, selenium, magnesium, phosphorus, and vitamins B and C can be of concern as you eliminate grains, legumes, and fruits from the diet. And let’s not forget fiber. All of those fiber-rich whole grains, beans, lentils and fruit have been eliminated, yet we need about 30g of fiber per day to support healthy digestion. While it is possible to get enough fiber on a keto diet, you have to be very intentional about it.
- Constipation: It ties back to the fiber. Not enough fiber increases the risk of constipation.
- Sustainability: As restrictive as a keto diet is, eating low-carb keto indefinitely is no easy task. First, the benefits of ketosis (reduced hunger, increased energy) only occur when you’re in a true state of ketosis. When you’re out, you’re out- those cravings and hunger are likely going to pay you a visit. Second, it can be difficult from a social standpoint. Think family gatherings and social events. And finally, an unhealthy obsession over how you eat and the keto “rules” can quickly spiral out of control, especially if you have a history of or are at risk of an eating disorder.
- The Keto “Flu”: When transitioning into ketosis, you may experience some unpleasant symptoms like nausea, headaches, lightheadedness, dizziness, muscle cramps, and fatigue. These symptoms can be a sign of a serious condition, like an electrolyte imbalance or low blood pressure. If you have a history of low blood glucose or low blood pressure, or are taking any medications, this is particularly important to be aware of.
Who should definitely not do the keto diet
Here’s what we do know: Women who are pregnant, people with liver and/or kidney disease, and those with fat malabsorptive disorders should definitely stray away from a ketogenic diet. For those who may be considering it, talk to your healthcare provider first so they are aware of the changes you plan to make to your diet and lifestyle and can properly advise and monitor.
The Bottom Line
The ketogenic diet could work for some people, but it’s definitely not for everyone. As with any diet, when you eliminate food groups there’s an increased risk of missing out on key nutrients and let’s be frank- there’s no getting around the sustainability issue (it’s not easy!). In fact, the 2018 US News & World Report ranked it second to last for “Easiest Diets to Follow.”
That said, we recognize that different things work for different people, and if done properly, this could be a viable option for weight loss and glycemic control. Just don’t feel like you have to jump on the bandwagon. There are many other healthy dietary patterns out there, ones we know more about, in terms of how it affects our long-term health.
If you do decide to give it a try, make sure you do so safely and correctly. A few things to consider:
- A modified vs. classic approach. Most experts agree that you can achieve ketosis under 50g per day, even higher for some. A modified approach may allow more flexibility, making it more do-able long-term.
- Taking a multivitamin or fiber supplement.
- Drinking plenty of water. Talk to your doctor about what that looks like for you.
- If you do not have a sodium restriction, drinking a cup of broth or bouillon to replace sodium. Sodium depletion can occur as you enter into ketosis.
- Limiting exercise, initially, while your body adjusts.
- Meeting with a Registered Dietitian who can help you tailor your meal plan to your personal needs.
*Non-diabetic ketoacidosis is rare but a few cases have been reported by individuals following a very low carbohydrate diet. Talk with your healthcare provider about this and any other concerns you may have.