High protein, low carb diets can work for weight loss in the short-term, but they do have risks so it is important to weigh up the evidence before you decide if it’s a good option for you.
Do high protein, low carb diets work?
While weight gain usually occurs over many years, many of us want a quick-fix solution to trim down. This may be one of the reasons that high protein, low carb diets have become popular again - they can give fast results in the short-term. But is losing a few kilograms in the short-term worth damaging your health in the long-term?
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What are high protein, low carb diets?
If you call it the Atkins Diet, South Beach Diet, Dukan Diet or Paleo – they are all very much the same. They tend to emphasise:
A high intake of animal proteins like red meat, chicken, fish and eggs;
Combined with a sharp reduction in carbohydrates including breads, rice, pastas, grains, legumes and fruits; and
In some cases, a high intake of fat is also encouraged, especially from nuts, seeds, extra virgin cold pressed olive oil, coconut oils, full-cream dairy products, butter and ghee.
While high protein diets may be getting some things right by encouraging plenty of vegetables and advocating no refined foods; there are other parts that you may want to reconsider.
How do high protein, low carb diets work?
They cut out the bad carbs. One of the main reasons these diets work in the short term is that they avoid all high-energy, low-nutrient refined carbs like soft drinks, cakes, lollies, biscuits, hot chips and crisps. But this advice is not unique to high protein, low carb diets – it is a good idea for anyone wanting to lose weight and live a healthy lifestyle to reduce their intake of refined carbohydrates.
They cut out entire food groups. By cutting out any food groups (like wholegrains, legumes and dairy) you restrict your food choices and therefore eat less. This may seem advantageous, however, it can result in you missing out on important food nutrients!
They dampen your appetite. Proteins and fats tend to be more filling, as they can take more time to digest. However, don’t forget that wholegrain carbohydrates and legumes are very filling too because they’re packed with fibre, dampening your appetite so you do not crave as much food.
What about the long term?
The main concern with high protein, low carb diets is that they are difficult to maintain over the long term and they tend to be nutritionally unbalanced.
Hard to maintain. Cutting out carbs does mean you are likely to eat less energy overall. But this is almost impossible to maintain over the long term. A study tracking 3000 people who lost over 30kg and kept it off for more than 5 years, found that less than 1% had followed a high protein, low carb diet. The rest reported consistently eating a low fat, high carbohydrate diet combined with regular exercise. The high protein dieters also maintained their weight loss for less time than the others and were also less physically active, possible due to having lower energy levels.
Out of whack and unbalanced. While there is no standard definition for 'high protein' some of the popular diets can have protein levels more than double the amount advised in the Australian Dietary Guidelines. They also tend to have very high levels of saturated fat and dietary cholesterol and cut out or limit whole grains, starchy vegetables and fruits, which are all important weapons against lifestyle disease, including heart disease, stroke and diabetes. This unbalanced approach to eating can have side effects and more serious long-term health impacts.
Risks of high protein, low carb diets
High protein, low carb diets do have risks – these range from common side effects to more serious long-term health impacts.
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Side effects
Some of the common side effects reported by people on high protein, low carb diets are:
Bad breath: When there is not enough carbohydrate in your diet, the body needs to turn proteins and fats into carbohydrates. In the process acetone vapours are released making your breath (and wind) smelly.
Constipation: Having too much protein and not enough fibre (from wholegrains, legumes, fruits and vegetables), can make you feel uncomfortable and constipated.
Lack of energy and irritability: Wholegrain carbohydrates help to fuel your body and keep your energy levels at their best. Cutting your carbs will leave you feeling tired, restless and less motivated to do your afternoon gym session.
Serious health impacts
Along with these more commonly reported side effects, there are more serious health concerns with high protein, low carb diets. These include:
Your bones. Too much protein can increase calcium loss in your urine, and it may increase your risk of osteoporosis, especially if you don’t have enough calcium in your diet.
Your heart. Too much saturated fat from the fat on meat, full-cream dairy products, coconut fat, butter and ghee can clog blood vessels and increase your risk of heart disease. A study showed that following a high protein, low carb paleo diet for over 10 weeks can increase your bad 'LDL' cholesterol by 20 per cent and decrease your good ‘HDL’ cholesterol even when exercising!
Your kidneys. A high protein intake makes your kidneys work harder, which will contribute to the decline in kidney function if you have kidney problems.
Your brain. A high intake of red meat and full-cream dairy products and a reduction of wholegrains, legumes, fruits and vegetables can increase your brain’s risk of diseases like Alzheimer’s and dementia.
Your lifespan. According to a new study, reducing your protein intake may also increase your lifespan and slow down aging.
Cancer risk. Diets high in red meat and low in protective plant foods are linked with an increased risk of cancer, particularly colon cancer.
Diabetes risk. Recent research also suggests that diets high in red meat may also increase your risk of type 2 diabetes.
Because of these risks there are some groups of people who should definitely avoid high protein diets. This includes people who are predisposed to kidney stones, have kidney disease or impaired kidney function; people with gout, diabetes, high blood cholesterol or high blood pressure; and people who are pregnant or breastfeeding. However, it’s best you speak to your doctor if you’re unsure.
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So while high protein, low carb diets can work for weight loss in the short-term, it is definitely not worth damaging your health for in the long-term. There is an alternative!
A wholicious approach to healthy eating
Don’t be afraid of carbs! Just choose the right ones. The type of carbohydrates in your diet matter, as do your portion sizes. If you want to lose weight, stick to the recommended serving sizes and number of serves per day. Also choose wholegrain or wholemeal breads, high fibre cereals and brown rice, in place of refined carbohydrates from foods such as white bread, highly processed cereals and white rice. Vegetarians who based their meals on good quality carbs are the healthiest groups of people in the world.
Choose plant proteins. If you want to increase the amount of protein you eat, try doing it with more plant proteins, like legumes and pulses. Not only will they help fill you up, they are one of the foods most associated with living a longer, healthier life.
Healthy fats. Just like with proteins and carbohydrates, including more healthy fats in your diet, like those in avocados, nuts and olive oil, can be a good way to fill you up, help manage your weight and reduce your heart disease risk.
Get active. Moving more is an important way of keeping a healthy weight. Successful weight loss is best achieved by aiming for 60 minutes most days in your week. If that sounds daunting, start with 20-minute sessions and gradually build up your exercise time as you get fitter.
