Why low carb diets are killing your results.
It seems that one of the “fashions” in diet trends that refuses to die, is the low carb approach. Whether you label it Atkins, keto or simply “low carb”, it never ceases to amaze me how well this seems to stick around. And yet, I don’t see the same proportion of people who have success from a health and performance perspective, as I do those waxing lyrical about it. So why is it so talked about and why does it have such a high failure rate?
Low carbohydrate diets often result in weight loss among the general population due to several key factors that interact with the body’s metabolism and eating behaviors. Understanding these mechanisms can provide insight into why such diets are popular and why they can be effective in the short term for weight loss:
1. Reduced Caloric Intake
One more time for the people at the back: fat loss/weight loss will only happen if you’re putting fewer calories IN than you’re using for output. Low carb diets quite often result in weight loss simply because they’re another way to manipulate you into putting less energy into the system.
- Satiety Increase: Low carbohydrate diets typically emphasise higher intakes of protein and fat, which can be more satiating than carbohydrates. This increased feeling of fullness can lead to a natural reduction in overall calorie intake.
- Elimination of Highly Processed Foods: These diets often eliminate many sources of processed and high-sugar foods, which are calorie-dense and easy to overeat. By cutting out these foods, individuals inadvertently reduce their calorie intake.
2. Glycogen Depletion and Water Loss
When carbohydrates are restricted, the body uses up its glycogen stores (carbohydrates stored in the liver and muscles). Glycogen is stored with water, so when glycogen is depleted, the body also loses a significant amount of water weight. This can result in rapid weight loss in the first few weeks of a low carbohydrate diet, which is often mistakenly perceived as fat loss, but is in fact, you mainly weeing your weight out.
3. Metabolic Changes
This is what seems to excite everyone…because people don’t understand nutrition and physiology properly…
- Increased Fat Oxidation: With lower carbohydrate availability, the body is forced to use more fat as a fuel source. This increased fat oxidation can contribute to weight loss BUT ONLY in the context of a calorie deficit as mentioned above.
- Ketosis: In very low carbohydrate diets, the body enters a state called ketosis, where it produces ketones from fats to use as an alternative energy source. Ketosis can also suppress appetite, contributing further to reduced calorie intake and consequent weight loss.
4. Hormonal Effects
In theory, reducing the spikes in blood sugar can help you to lose weight by avoiding the peaks and troughs of insulin and glucose spikes. Some of this suggestion is a bit crap, but it is true to suggest that consuming high glycemic index foods (i.e. those rich in available simple carbohydrates) could leave you feeling hungrier more often where fat, fibre and protein are missing from slowing down the digestion of these foods, which could make it harder to avoid over-eating.
BUT.
While low carbohydrate diets can be effective for short-term weight loss, they may not be sustainable or healthy for everyone in the long term – something I’ve addressed in the blog and free weekly newsletter many times over . The rapid weight loss experienced initially is largely due to water loss, not necessarily fat loss. Moreover, such diets can lead to nutritional deficiencies if not carefully planned to include a variety of nutrient-dense foods. It’s also worth noting that long-term adherence to a very low carbohydrate diet can be challenging for many people, leading to weight regain once a normal diet is resumed.
All these caveats are WORSE STILL for athletic populations. Here’s why:
1. Reduced Energy Availability
For athletes, glycogen is a critical energy source, especially during high-intensity and endurance activities. Low carbohydrate intake means reduced glycogen stores, leading to decreased performance, early onset of fatigue, and impaired endurance capacity. While the initial excitement of glycogen and water based weight loss is great, after not so long, it’s going to feel pants. And you’ll be sad.
2. Impaired Recovery
Your muscles are your powerhouse! You need to feed and maintain them, build them and improve them. We often think of protein as the essential here, but what about the important role carbs play?
Adequate carbohydrate intake post-exercise is crucial for replenishing glycogen stores and facilitating muscle repair through insulin-mediated pathways. Insufficient carbohydrate intake can slow recovery, increasing the risk of overtraining and injury. In the absence of sufficient carbohydrates, the body may even use protein as an energy source, diverting it from its primary role in muscle repair and growth. This means you may well struggle to maintain your muscle mass, let alone trying to build and improve your strength.
3. Nutritional Deficiencies
Carbohydrate-rich foods like fruits, vegetables, and whole grains are key sources of vitamins, minerals, and fiber essential for overall health. Restricting these foods can lead to nutritional deficiencies, impacting energy levels, immune function, and long-term health, not just a dip in performance. The initial rapid weight loss from water associated with glycogen depletion can also lead to dehydration, which we all know ain’t going to help you in training, particularly if you\re interested in heat-stress training and performing hotter climes.
4. Metabolic Flexibility
Contrary to popular belief, you’re never just burning one thing. You also have the capacity as a human to rely on different fuel sources at different times – this is one of the things that has helped human beings to be possibly the most successful species on the planet (absolutely shocking reality when you think about how we behave as modern humans but there we are…). Athletes benefit from being metabolically flexible, meaning you can efficiently switch between burning carbohydrates and fats as fuel sources depending on the activity’s intensity and duration. A chronic low carbohydrate intake can impair this flexibility, making it harder to get bang for your buck across the range of workouts you inevitably need to be able to complete to really edge your way up in training as an endurance athlete.
5. Mood and Cognitive Effects
Carbohydrates have a direct impact on serotonin levels, a neurotransmitter that regulates mood. Low carbohydrate intake can lead to mood swings, irritability, and decreased cognitive function. Basically, nobody wants you showing up like a Moody Mary to training, because that really sucks the fun out of the session. So eat your carbs to avoid being the day’s dementor.
6. Disordered Eating
Strict rules and regimens around food and eating are the very reason I exist in the world of nutrition. The world of sport is already full of people battling with hang-ups around food and exercise and body image, whether they’re aware of it or not. What you DON’T need is a whole heap of other rules to exacerbate this in an environment where it’s already hard to avoid that.
It’s easy to get sucked into quick fixes and trends when you’re feeling anxious and overwhelmed when it comes to how you look and feel in your lycra. But you will ALWAYS benefit more in the long term from taking a balanced perspective. And if that seems hard – perhaps even impossible – right now, then maybe it’s time to consider working with a professional to help you:
- Tailor Your Diet to Your Unique Needs: Your history, your attitude, your lifestyle, your training. What works for used-to-be-fat-Matt down the road, ain’t necessarily going to be the problem solver for you.
- Improve Performance and Recovery: That age old complaint of “I’m just tired all the time and I never feel ready for the next session”. Learning what works for YOU in terms of recovering between sessions – again, including all you individual circumstances.
- Ensure Nutritional Adequacy: Putting your long-term human health FIRST, which is the most stable, reliable and effective foundation to have as an athlete.
- Foster a Healthy Relationship with Food: Move away from restrictive diets and towards a more flexible approach to eating. A nutritionist can help you find joy in eating healthily, reducing anxiety around food and promoting positive eating and exercise habits.
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