January is renowned for people desperately counting calories to regain control after Christmas and get themselves back on the wagon of all things healthy.
I frequently get asked how many calories people should consume on a daily basis. The simplest answer, though not the most helpful, is the general health recommendation: for a woman- approx 2000 a day and for a man- approx 2400 a day. While calorie counting can be a start point when it comes to trying to lose weight, the quality of those calories and indeed the impact of the type of calories on your blood sugar is paramount. By ‘quality’ I refer to both the nutrient quality and how well the particular calorie from it’s particular food group interacts with metabolism.
When we eat we produce insulin which moves sugars from our bloodstream to our muscles and liver and any excess in to our fat stores. Insulin is a necessary hormone, we couldn’t function without it but the amount that we produce and the speed at which we produce it is of huge significance when it comes to weight / fat loss.
Refined carbohydrates (bread, pasta, rice, all simple sugars, flour), due to being very high in what the body perceives as sugars, are broken down very fast leading to a spike in blood sugar. The body strongly objects to spikes in blood sugar so as a result it will pump out insulin to lower blood sugar by moving sugar from blood stream to muscles, liver and fat cells in order to achieve homeostasis within the blood stream. The more carbohydrate we eat, the more insulin we produce and the more fat we store. While insulin levels are high, the body is also prevented from accessing energy from it’s fat cells meaning that we can’t burn our body fat. Here we have a double whammy of insulin encouraging fat storage and also preventing fat burning.
Proteins and fats have much less impact on blood sugar levels meaning that less insulin is produced and what is produced is produced at a slower rate meaning less fat storage and more fat burning.
In terms of satiety, the calorie is not equal from all food groups either. Fats and proteins have far more impact on reducing hunger than carbohydrates alone do. Admittedly there are carbs and carbs: very refined white bread that has very little nutritional value and sends blood sugar and insulin soaring is simply not worth eating but sweet potato, a very natural and nutrient dense food, is a valuable part of any diet as long as it is well timed (e.g. eaten on a more active day) and eaten in the presence of fats and proteins which will slow down the break down of sugars and therefore slow down insulin production (e. g. sweet potato eaten alongside salmon with a drizzle of olive oil will be digested more slowly than sweet potato alone).
The Diet Delusion by Gary Taubes is worth the read if you have the time. He sums up the satiety issue by saying ‘it’s possible to eat up to 10,000 calories of mostly carbohydrates and be hungry at the end of the day, whereas eating a third as many calories of mostly fat and protein will more than satiate us.’ (Taubes, The Diet Delusion 2007 p341)
So how does this translate in terms of what we should be putting on our plates? Basically, go natural. If you base your diet around protein, fruit, veg, nuts, seeds and oils and moderate amounts of natural carbohydrates (e.g. oats, sweet potato, brown rice) you will achieve your goal.
For those who like to know how many calories they should be eating, if your calories come from the food groups specified above then the general guidelines of 2000 for women and 2400 for men will work to maintain weight, and with a bit of reduction, to lose body fat.
To summarise: if you eat 2000 calories of cake a day, you will gain weight due to the insulin response and associated fat storage and inadequate fat burning. If you eat 2000 calories a day of steak and spinach, you will lose weight. And, no, wholemeal flour doesn’t make cake fall in to the ‘natural’ carbohydrate category.