Losing weight is always a struggle, and those who have tried, know the challenge of dropping that last five pounds.

Apparently, there is a scientific reason why it's so hard. An obesity expert reveals what one should do when one hits the weight loss plateau.

Losing the last few pounds can be really frustrating, knowing that you’re still following the same diet, lifestyle habits, and exercise plan. However, the weight-loss plateau is “basic biology,” according to Nick Fuller, Charles Perkins Center Research Program leader, University of Sydney.

The human body is an extremely efficient machine. It has many tricks up its sleeves. The body deploys various mechanisms when it feels under threat. Therefore, when we cut down our calorie intake, our body senses that weight loss, and thinks of it as a threat. Consequently, the body reduces the metabolic rate and burns less energy, as per ScienceAlert. In other words, it slows the rate at which one loses weight.

Moreover, the body increases the secretion of an appetite hormone called ghrelin, which increases hunger and aids the conservation of fat stores. According to research, weight loss plateaus occur between three and six months of losing weight and usually end with weight regain. This means for those trying to lose a large amount of weight, the plateau will occur way before the last five kilos.

However, this does not mean that one simply gives up. There are a few ways to manage the issue of weight loss stagnation during diet.

Rethink the weight-loss goal

Fuller said the most important aspect of losing weight is knowing the definition of healthy body weight.

“Many people use the body mass index (BMI) to set their weight-loss goal, but the number on the scales – and the score generated when you enter your weight and height into the BMI calculator – is nonsense. It doesn't tell the whole story of what it means to be a healthy weight,” the expert said.

This is so because BMI does not take into account two measures: body fat percentage and body fat distribution.

Regular exercise leads to muscle gain. The resulting improved muscle-to-fat ratio will impact the weight measure, since muscle is heavier than body fat. Also, the fat distribution may change due to the weight-loss plan. Exercise can transfer the amount of unhealthy fat stored around the waist closer to organs, which is great for reducing the risk of disease.

“Work towards a waist circumference of about 80 cm for women and about 90-94 cm for men,” Fuller advised.

Do not skip meals

Intermittent fasting or skipping breakfast is a big folly. The amount of food and the timing of the meals plays an important role.

“Controlled research studies have shown this is the time [breakfast] when your body best uses the calories you put in – in fact, it burns the calories from a meal two-and-a-half times more efficiently in the morning compared with the evening,” Fuller explained.

Review food intake

Food intake should be commensurate with body weight, as less body weight means the body needs less fuel to go through the day.

“Generally speaking, you need to consume 10% fewer calories when you reduce your weight by 10 percent, just to maintain the new weight. But this shouldn't mean deprivation or starvation,” Fuller said. “Instead, you should be focusing on an abundance of nutrient-dense foods and keeping the treats and takeaway to just once per week.”