The ‘no carbs after 5pm’ has been a mantra for people on diets trying to lose weight for more than 10 years. But is this principle fact or fiction? Does it really make any difference whatsoever?
Effectively, the advice was to eat little or no bread, pasta, pizza or rice and various other foods and sauces containing carbohydrates such as desserts and puddings.
The strategy was originally intended as a total calorie reduction strategy, rather than a ban on a particular food type. It meant that you lowered your overall calorie intake for the day, and perhaps ate more protein that filled you up and staved off the hunger pangs for longer. This especially applied to processed carbohydrate such as pasta, bread, desserts, puddings and sauces made using white flour.
The diet encouraged people to eat carbohydrate rich foods for breakfast and lunch, with emphasis on low or moderate GI carbohydrate.
For the evening meal the idea was to eliminate the carbohydrate by saying ‘No!’ to jacket potatoes and pumpkin with a roast dinner, no spaghetti Bolognese and no rice with your stir fry and curry dishes.
However, it appears that many people simply ate more fat and protein and more carbohydrate at breakfast and lunch, which reduced any lowering of daily calories.
Recent research has suggested the complete opposite principle: Consuming carbohydrates in the evening may be beneficial for weight loss through hormonal changes that reduced hunger and the feeling of satiety and fullness.
A new large study in Israel that involved overweight women and policemen found that when the subjects consumed the majority of their daily carbohydrate with the evening meal rather than at breakfast and lunch the levels of the hormone ‘leptin’ were increased.
This hormone that has only recently been discovered is responsible for satiety, that is, it tells us when we’re feeling full. This is quite different to the feeling of hunger which involved different hormones.
When people are dieting by restricting food and calorie intake their leptin levels fall because they are consuming less food. This makes them feel hungrier and gives them a sense of having an empty stomach.
Controlling hunger and generating a sense of fullness by eating high fiber and bulky low calorie foods, is one of the most important requirements for weight loss. Hunger and a sense of an empty stomach can sabotage efforts to lose weight.
However the research found that when people consumed most of their carbohydrates at dinner it produced higher levels of leptin, which reduced and delayed their feelings of hunger. The levels of cholesterol, blood glucose and insulin were also improved compared when carbohydrates were not eaten at dinner.
The message is clear: There is no weight loss magic attached to changing when carbohydrates are eaten throughout the day.
Similarly the claims that calories in protein, fat and carbohydrate is somehow different has also been disproven. Many had claimed that you could eat more calories derived from protein, because it has a discounted effect on energy intake.
Similarly the claim that there are ‘negative calorie’ foods such as celery has been disproven. This suggested that certain vegetables required more calories to digest and process via metabolism than they contained.
The study results do not suggest that over-eating starchy or sugary carbs at the evening meal will somehow reduce your appetite and mean that you will consume less at other meals.
But rather, moderate amounts of quality complex carbohydrate with plenty of fiber can help control the hunger pangs for longer, so you will be less likely to grab a late-night snack.
The researchers suggested focusing of dinner that included whole grains and other carbohydrates low GI levels such as brown rice, real sourdough bread made with wholemeal flour, legumes and green leaf vegetables.
Eating a hearty evening meal with sensible servings of carbohydrates may help in other ways – it may help you sleep better. Lack of sleep can ruin a weight loss program.