Obesity and metabolic diseases are major health problems worldwide.
In 2016, obesity affected 13% of adults globally.
Obesity is a risk factor of metabolic syndrome, a cluster of metabolic abnormalities, including type 2 diabetes, high blood pressure, high waist-to-hip ratio, and low HDL (good) cholesterol.
To combat this, many diets have emerged, including the ketogenic diet, in which a person consumes a very limited amount of carbohydrates. Some research suggests this diet may have benefits for people with obesity.
However, some experts have questioned the health benefits of the keto diet and called for more research. While it may help you lose weight, there may also be complications.
This article explains how the keto diet may help people lose weight and manage the metabolic disease. It also discusses some of the possible drawbacks.
- What is a ketogenic diet?
- Ketogenic diets and weight loss
- How do ketogenic diets promote weight loss?
- A ketogenic diet and metabolic diseases
- Impact on metabolic disease
- How to follow a ketogenic diet
- Should you try a ketogenic diet?
What is a ketogenic diet?
A ketogenic diet is high in fat, moderate in protein, and low in carbs.
As carbs are reduced and fat increases, the body enters a metabolic state called ketosis. Then the body starts turning fats into ketones, molecules that can supply energy for the brain.
After a few days or weeks on such a diet, the body and brain become very efficient at burning fat and ketones for fuel instead of carbs.
The ketogenic diet also lowers insulin levels, which can be beneficial for improving insulin sensitivity and blood sugar management.
Staple foods on a ketogenic diet include:
- heavy cream
- low carb vegetables
In contrast, nearly all carb sources are eliminated, including:
- some higher-carb vegetables
Summary: A ketogenic diet is a high-fat, moderate-protein, and low-carb diet. It primarily works by lowering insulin levels, producing ketones, and increasing fat burning.
Ketogenic diets and weight loss
There’s evidence that ketogenic diets can help with weight loss.
They may help you lose fat, preserve muscle mass, and improve many disease markers.
Some studies have suggested that a ketogenic diet may be more effective than a low-fat diet for weight loss, even after matching the total calorie intake.
In one older study, people on a ketogenic diet lost 2.2 times more weight than those on a low-calorie, low-fat diet. Triglyceride and HDL (good) cholesterol levels also improved.
However, both groups reduced calorie consumption by a comparable amount, which may have increased weight loss.
Another 2007 study compared a low-carb diet to the Diabetes UK’s dietary guidelines. It found the low-carb group lost 15.2 pounds (6.9 kg), while the low-fat group lost only 4.6 pounds (2.1 kg). Over three months, the low-carb diet caused three times more weight loss.
However, the groups had no difference in HbA1c, ketone, or lipid levels. Also, those on the low-carb diet also decreased their calorie intake. Finally, the two groups had no difference in fat or protein intake. This is important to note if people are increasing their fat intake because they are following a keto diet.
However, there are contrasting theories for these findings. Some researchers argue the results are simply due to a higher protein intake, and others think there’s a distinct “metabolic advantage” to ketogenic diets.
Other ketogenic diet studies have found that the ketogenic diet may lead to reductions in appetite and food intake. This is extremely important when applying the research to a real-life setting.
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The data suggests a ketogenic diet may be a good option if you dislike counting calories. You can eliminate certain foods and don’t have to track calories.
If you follow the keto diet, you still have to check labels and track your total grams of carbs daily, which requires paying attention to food choices.
However, remember that many of the studies mentioned above had small sample sizes and only evaluated the short-term effects of the diet.
Additional research is needed to determine how the diet may impact weight loss in the long run and whether weight is regained once a regular diet is resumed.
Summary: The ketogenic diet is an effective weight loss diet supported by evidence. It is very filling and usually does not require calorie counting.
How do ketogenic diets promote weight loss?
Here’s how ketogenic diets promote weight loss:
- Higher protein intake. Some ketogenic diets lead to an increase in protein intake, which has many weight loss benefits.
- Gluconeogenesis. Your body converts fat and protein into carbs for fuel. This process may burn many additional calories each day.
- Appetite suppressant. Ketogenic diets help you feel full. This is supported by positive changes in hunger hormones, including leptin and ghrelin.
- Improved insulin sensitivity. Ketogenic diets can drastically improve insulin sensitivity, which can help improve fuel utilization and metabolism.
- Decreased fat storage. Some research suggests ketogenic diets may reduce lipogenesis, the process of converting sugar into fat. This is because excess carbs are stored as fat. Fat is used for energy when there’s a minimal intake of carbs.
- Increased fat burning. Several studies have found that ketogenic diets may slightly increase the fat you burn during rest, daily activity, and exercise, although more research is needed.
In these ways, a ketogenic diet can be effective at helping you lose weight.
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However, note that it’s essential to ensure that you meet your calorie needs when following the ketogenic diet. Cutting calories too much can slow your metabolism, making it harder to lose weight in the long run.
Some experts also note that, while the keto diet may lead to weight loss in the short term, the loss is unlikely to continue. It can also be hard to follow the diet for a long time.
Summary: A ketogenic diet may help burn fat, reduce calorie intake, and increase feelings of fullness compared to other weight-loss diets.
A ketogenic diet and metabolic diseases
Metabolic syndrome describes five common risk factors for obesity, type 2 diabetes, and heart disease:
- high blood pressure
- high waist-to-hip ratio (excess belly fat)
- high levels of LDL (bad) cholesterol
- low levels of HDL (good) cholesterol
- high blood sugar levels
Many of these risk factors can be improved — or even eliminated — with nutritional and lifestyle changes.
Insulin also plays a vital role in diabetes and metabolic disease. Ketogenic diets are highly effective for lowering insulin levels, especially for people with type 2 diabetes or prediabetes.
One older study found that after only two weeks on a ketogenic diet, insulin sensitivity improved by 75%, and blood sugar dropped from 7.5 mmol/l to 6.2 mmol/l.
A 16-week study also found a 16% reduction in blood sugar levels. Additionally, 7 of the 21 participants could stop all diabetic medication completely.
Moreover, some studies in humans and animals have also found that the ketogenic diet could reduce levels of total cholesterol and triglycerides.
However, note that most available research only focuses on the short-term effects of the ketogenic diet.
Some older studies suggest that the ketogenic diet may negatively affect heart health, particularly in children.
Additionally, although research shows that saturated fat intake is not directly linked to a higher risk of heart disease, it may increase levels of LDL (bad) cholesterol, a risk factor for heart disease.
Furthermore, several studies also show that consuming high amounts of some types of fat may be associated with a higher risk of certain types of cancer.
Therefore, more research is needed to determine how the ketogenic diet may affect long-term health and disease.
Summary: Ketogenic diets can improve many aspects of the metabolic syndrome, a significant risk factor for obesity, type 2 diabetes, and heart disease.
Impact on metabolic disease
Several key factors explain the drastic effects of the ketogenic diet on markers of metabolic disease. These include:
- Fewer carbs. A high-carb diet can constantly elevate blood sugar and insulin levels, decreasing the body’s ability to use insulin efficiently.
- Decreased insulin resistance. Insulin resistance can cause health issues like inflammation, high triglyceride levels, and fat gain.
- Ketone bodies. Ketone bodies — molecules produced during ketosis — may help protect against some diseases, such as cancer, Alzheimer’s, and epilepsy.
- Inflammation. The ketogenic diet can drastically reduce chronic inflammation linked to metabolic syndrome and various diseases.
- Fat loss. This diet promotes body fat loss, especially unhealthy abdominal fat. Excess fat in the abdominal area is a criterion for metabolic disease.
- Restore normal insulin function. Research has shown that healthy insulin function can fight inflammation, while poor insulin function can increase it.
As you can see, the combination of these factors plays a rather remarkable and important role in health and protection against disease.
Summary: Ketogenic diets may improve metabolic health by improving insulin function, lowering inflammation, and promoting fat loss.
How to follow a ketogenic diet
If you want to try a ketogenic diet, follow these basic rules:
- Eliminate carbs. Check food labels and aim for 20 to 50 grams of carbs or fewer per day.
- Stock up on staples. Buy meat, cheese, whole eggs, nuts, oils, avocados, oily fish, and cream, as these are now staples in your diet.
- Eat your veggies. Fat sources are high in calories, so base each meal on low-carb veggies to fill your plate and help keep you feeling full. Veggies will also provide fiber, which you’ll no longer be getting from whole grains, beans, or legumes.
- Experiment. A ketogenic diet can still be interesting and tasty. You can even make ketogenic pasta, bread, muffins, brownies, puddings, ice cream, etc.
- Build a plan. It can be hard to find low-carb meals for when you’re on the go. As with any diet, it’s essential to have a plan and go-to snacks or meals.
- Find what you love. Experiment until you find the ultimate keto diet for you.
- Track progress. Take photos, measurements, and monitor your weight every 3 to 4 weeks. If progress stops, re-examine your daily intake. Ensure you’re getting enough vegetables at every meal, and keep portions moderate.
- Replace fluids. Make sure you’re drinking enough water and getting proper amounts of electrolytes, like sodium, potassium, and magnesium.
- Be consistent. There’s no shortcut to success. With any diet, consistency is the most crucial factor.
You may also wish to monitor ketone levels in either urine or blood since these let you know whether you’re keeping carb levels down sufficiently to achieve ketosis.
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Based on current research, studies at my lab, and continuous testing with clients, anything over 0.5–1.0 mmol/l demonstrates sufficient nutritional ketosis.
Before switching to this type of diet or using any type of supplement, ask your doctor or a dietitian for advice.
Summary: Base most of your meals on low-carb veggies, high-fat meats, fish, or eggs. You may also wish to monitor your ketone levels.
Should you try a ketogenic diet?
No single diet is suitable for everyone, mainly since individual metabolism, genes, body types, lifestyles, taste buds, and personal preferences differ.
It can benefit people with obesity or who have a higher chance of developing metabolic syndrome, but it’s not suitable for everyone. For example, it’s not suitable for people with the following conditions:
- liver failure
- disorders of fat metabolism
- carnitine deficiency
- pyruvate kinase deficiency
There may also be some adverse effects. When you first start the diet, you may experience flu-like symptoms, known as “keto flu.”
This may include poor energy and mental function, increased hunger, sleep issues, nausea, digestive discomfort, and poor exercise performance.
Researchers have not yet done enough long-term investigation to determine precisely the long-term effects, but there may be a risk of kidney or liver problems.
There’s also a risk of dehydration, so you must drink plenty of fluids, especially water, while following this diet.
Always speak to a doctor before starting a ketogenic diet to ensure that it’s safe and suitable for you.
A ketogenic diet can also be hard to stick to. If you can’t follow it but still like the idea of a low-carb diet, then carb cycling or a standard low-carb diet may be a better option for you.
A ketogenic diet may also not be the best option for elite athletes or those wishing to build large amounts of muscle.
Additionally, vegetarians or vegans may struggle with this diet due to the key role meats, eggs, fish, and dairy play.
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Summary: The ketogenic diet can provide excellent results if you stick to it. However, it may not be the best option for everyone.
To get the most out of a ketogenic diet, you must eat high-fat foods and limit your carb intake to fewer than 30–50 grams daily.
If you follow a ketogenic diet with medical supervision, it can help you lose weight, and it may enhance your overall health.
It may reduce your risk for type 2 diabetes, obesity, and other aspects of metabolic disease.
Before starting any new diet, remember to ask your doctor if it’s a suitable option for you.