By vegan naturopath Robyn Chuter.
For years, I’ve been hearing from clients that their personal trainer/nutritionist/astrologer (OK, I made that last one up) told them not to eat ‘carbs’ after 4 pm, or 6 pm, or whatever particular witching hour their self-appointed weight-loss guru nominates, if they want to lose weight.
The popular theory goes that eating a lot of carbohydrate-rich food stimulates excessive insulin release, and that since we’re less active at night than during the day, all that insulin will cause the glucose we absorb from starches to convert to fat. This theory is quoted as gospel truth on gazillions of weight-loss websites… but it turns out it’s completely false.
A recent study compared the outcomes of 78 obese police officers who were put on a low calorie diet containing 20% protein, 30-35% fat and 45-50% carbohydrate. The control group was told to distribute their carbohydrate intake throughout the day, while the experimental group was instructed to eat most of their carbohydrates at night.
The researchers found that, after 6 months of following the dietary plan, the carbohydrate-at-night group had lost substantially more weight, abdominal girth and body fat mass than the control group, despite the two diets containing the same calories and the same proportions of macronutrients.
Furthermore, the carbohydrate-at-night group experienced less hunger and had greater improvements in fasting glucose, average daily insulin concentrations, insulin resistance, cholesterol and the inflammation markers C-reactive protein, tumor necrosis factor-a, and interleukin-6, which are elevated in overweight people, and are linked to an increased risk of heart disease, cancer and depression.
Although you wouldn’t know it from reading popular weight loss books and websites, the idea that carbohydrate-rich foods caused increased insulin secretion was debunked last century, in a study that examined the insulin demand generated by various foods.
Researchers fed 1000 kj portions of a variety of foods to healthy people, and measured the amount of insulin their bodies secreted in response. They found that both protein-rich foods and bakery products (which are high in fat as well as carbohydrate) elicited disproportionately high insulin secretion.
Beef and cheese, for example, raise insulin levels more than pasta!
Even earlier research found that glucose raised insulin secretion only slightly more than an equivalent amount of protein.
The bottom line here is that popular theories of weight loss should never be used as the basis of your weight loss plan. There is no substitute for properly-conducted testing of these theories, no matter how ‘scientific’ their proponents make them out to be.
The scientific literature is, in fact, very clear about what works for sustainable weight loss – a diet based on unrefined plant foods. See my articles Eating meat: the fast track to diabesity, and The Big Fat Protein Swindle for more information and scientific references.