The science of fat loss: ‘I dropped two dress sizes by going “slow carb” — and I have so much more energy’
You don’t have to go ‘full keto’ in order to lose weight, Regina Lavelle found as she investigates the many incarnations of the low-carb diet and the benefits they can bring
Steak but no potato? Bacon and egg but not porridge? Butter but no toast? Unleashed on a public broadly conditioned to associate diets with salads, low-fat yoghurts, and calorie counting, lowcarb diets viewed our bodies as a complex system that could be rewired to operate differently. Peppered with words like ‘ketosis’, low-carb logic meant our conventional nutritional narrative needed a total rewrite.
A low-carb diet involves cutting out much of the starchy foods — breads, rices, pasta — from our diet and reducing our total carbohydrate intake to 20pc of our overall consumption and increasing protein and, sometimes, fat intake.
Mark Germaine, performance nutritionist and researcher at DCU’s School of Health and Human Performance explains what happens with a high carbohydrate diet.
“When you ingest carbohydrate, you eventually get an increase in glucose levels in the blood. The pancreas detects this increase and releases insulin in response. The purpose of insulin here can be seen as two-fold. Firstly, it stores glucose in the cell, thus clearing the high levels from the blood.
“And second, it stops the body breaking down fat for energy and it stops the liver producing glucose.”
So insulin speeds up the process of storage of glucose, and slows down the process of breakdown of stored glucose. But fewer carbohydrates equals less insulin, equals less glucose stored, and more glucose stored in fats released for consumption as energy. This process of breaking down stored fats for energy is called ketogenesis or ketosis.
Low-carb diets can be ketogenic but only in specific circumstances.
“A point often missed is that a low-carb diet is not always ketogenic if protein intake is high and fat intake is not high enough. It is a combination of the low carb and high fat that drives ketogenesis,” says Dr Brendan Egan, associate professor of sport and physiology at DCU’s School of Health and Human Performance.
Ketosis and low-carb diets are often conflated, however ketogenesis is not required for low-carb diets to be beneficial, or even to produce weight loss.
There are many positive examples of other benefits.
Sarah Ann Behan (38) started a ‘slow carb’ regime — slow-release carbohydrates — to address general unwellness and weight gained following surgery.
The surgery affected her ability to digest
‘I do find that the more you do it, the more you get into prepping your breakfast, making your own meals, you do it so slowly you don’t notice it becoming a habit’
certain foods, particularly high-fibre and wholegrains and post-surgery, the Courts Service executive found herself “exhausted, miserable, in pain and heavier”.
Under guidance, she began the regime, where she included slow-release carbohydrates into her diet. As Behan had additional restrictions on what she could eat, the changes came very gradually.
“We started in September. We would say, ‘OK, so let’s try this one thing this week and see how it goes’. And then we’d repeat.
“First I tried chickpea pasta, then I changed the type of bread I was eating.
“I started pre-soaking porridge or granola and taking time to eat that.”
It sounds like a lot of additional prepping and cooking, but Behan says it was easy to find workarounds, especially during the first few weeks.
“There are pre-made soups that you can buy if you’re running out of time. It’s really handy and relatively cheap.”
Five months in, she finds herself less likely
‘There’s no point going on a low-carb diet if you love pasta and bread. You won’t stick with it. You could consider a Mediterranean diet, which is less red meat, but more vegetables, nuts, grains, legumes and pulses and olive oils. It’s about making small changes you can maintain and increasing exercise, rather than going on a diet,’ says Sinead Powell, senior dietitian with Diabetes Ireland
to opt for the pre-made options, as the gradual amendments have morphed into long-term changes.
“I do find that the more you do it, the more you get into prepping your breakfast, making your own meals, because you do it so slowly you don’t notice it becoming a habit.”
She has lost two dress sizes since September, which has “happened really accidentally. I didn’t feel hungry. I’m sleeping better and I’ve more energy”.
However, there have been concerns around the impact of low-carb, high-fat diets on heart health for those who are not aware of the risks. It is the low-carb diets that mandate a high-fat consumption, including many of those aiming for ketosis that can be a danger, particularly when the fats are saturated.
“Where low-carb diets include a high level of plant-based proteins, there can be reduced cardiovascular risk,” says Sarah Noone, dietician with the Irish Heart Foundation.
“With some low-carb diets, there can be a danger of developing high LDL, your bad cholesterol, which can increase cardiovascular risk.”
However, it’s not quite so clear-cut as saturated fats being bad and everything else good.
“The data still seems to indicate that high proportions of saturated fat negatively affect blood lipids [fats], and that replacing saturated fats with monounsaturated fats, polyunsaturated fats or high-fibre foods result in a better blood lipid profile,” says Germaine.
“That said, replacing saturated fats with sugary forms of carbohydrate can have adverse effects on blood lipids. If you are following a low-carb or ketogenic diet, it may be wise to prioritise monounsaturated and polyunsaturated fats over saturated fats, and ensure you are still getting in enough fibre-rich foods.”
There are other scenarios where nutritional science has almost reached a consensus about the value of low-carb diets. New Scientist has recently reported that both Diabetes UK and Diabetes Australia “say low-carbing is a valid option for weight loss”, adding that The American Diabetes Association said lowcarbing has “the most supporting evidence for improving blood sugar control”.
Sinead Powell, senior dietitian with Diabetes Ireland, agrees that people can underestimate the impact of carbohydrates, especially when we believe them to be healthy.
“Most of my teaching around diet is forget about just thinking ‘sugar’, understand carbs, understand portion size. A lot of adults are over-consuming what they believe to be good carbohydrates, the likes of porridge and wholegrain breads.
“Years and years of very big carb loads on your pancreas will make it work harder. And if you’re not getting enough exercise, excess calories will be stored as fat.”
It’s important, however, that we don’t single out carbs for demonisation.
“Overconsumption of protein, as well as either carbs or fat, can be problematic. Simply put, over-nutrition no matter what the macronutrient combination will cause insulin resistance,” says Dr Egan. “There is no need to increase protein intake disproportionately (i.e. over 30pc of energy intake) either as if it is some kind of panacea. “Most people could benefit from more protein at breakfast because that is often the meal that is lowest, and a protein-rich breakfast is likely to provide sustained energy, curb appetite and reduce snacking.
“As with most things about diet, you’d have to say smart eating and moderate intakes of protein is the way forward,” he adds.
Getting any diet right is a balancing act, and they both advocate gradual, incremental changes to dietary habits, rather than a ‘diet’, both citing research that few people are able to maintain restrictions in the long-term and many end up putting the weight back on inside 12 months.
Therefore, a new regime has to be something sustainable in the longterm and fit with your likes and dislikes as well as your lifestyle.
“There’s no point going on a lowcarb diet if you love pasta and bread,” says Powell.
“You won’t stick with it. You could consider a Mediterranean diet, which is less red meat, but more vegetables, nuts, grains, legumes and pulses and olive oils.
“It’s about making small changes you can maintain and increasing exercise, rather than going on a diet.”
The emphasis, agrees Noone, needs to be in favour of back to health, rather than simply weight. As with so much in life, there’s no short-cuts.
“Quick fixes can be very appealing, in contrast to the long-term approach, which can take a long time and be very challenging.
“What we know to work are small changes over time and adapting eating and lifestyle habits.
“That will mean any weight loss will be healthy and sustainable.”