Why it's harder to lose fat as you progress in your diet and why it's so easy to put it back on

As you diet you may find it gradually getting tougher to fight your appetite and lose fat. Truth is as we lose weight our bodies respond to the change and try to preserve our energy or fat stores. Changes in hormones and metabolism are the biggest factors in the increasingly difficult task of cutting weight and lose fat. Then once you reach your goal you might find it incredibly easy to put fat back on or put on even more than you started with! There are many natural reasons why these things happen.

First off hormones control many of the body’s responses and are important to understand. As weight decreases different hormones increase and decrease in the body. As for hormones that decrease you will see hormones such as leptin, insulin, thyroid hormones and even testosterone drop. Leptin is important for energy expenditure and satiety (feeling full.) In a study of lean bodybuilders preparing for competition they tested for their leptin changes three times at 11 weeks, 5 weeks, and 3 days before competition. Just at 5 weeks out their leptin levels dropped by 27.7% and dropped more when tested 3 days out. Insulin is helpful in preventing muscle protein breakdown and hunger. Thyroid hormones specifically triiodothyronine (T3) is important in increasing metabolism. Lastly, we have testosterone which help via its muscle building properties. In a study done with 19 male ameture wrestlers they found that very low body fat and or large losses of body fat adversely affected their serum testosterone levels. Now there are two important hormones that increase during cutting, ghrelin and cortisol. Ghrelin affects hunger and appetite and is what makes fighting the urges to eat even harder. In the same study that I mentioned above researchers found at the 5 week mark that ghrelin increase by 20.4% and found another 6% increase by 3 days out. Cortisol affects muscle protein breakdown so an increase in both of these hormones shows how losing weight becomes increasingly difficult.

Metabolism is huge in weight loss and it changes drastically when trying to lose fat. There are several important areas of metabolism REE (resting energy expenditure) which makes up BMR (basal metabolic rate), NEAT (non exercise activity thermogenesis), TEF (thermic effect of food), and EAT (exercise activity thermogenesis). In a study of obese men and women on a caloric restricted diet their REE decreased. It was noted that after eight weeks the men seen a 963 KJ/day drop in REE and women seen a 614 KJ/day drop, essentially meaning their metabolism slowed down. This is likely due to the body trying to conserve energy because it perceives the food caloric restriction as starvation. NEAT which includes activities such as walking around or even fidgeting is reduced on a caloric restricted diet further lowering energy you burn during normal daily activities. TEF (accounts for 10% of metabolism) and is reduced as you decrease food intake also essentially burning less as you consume less. Lastly we have EAT also goes down due muscle efficiency and due to loss of weight meaning it’s easier to perform tasks requiring less energy because you are moving less of your body weight. Overall, these aspects of metabolism come together to make your TDEE (total daily energy expenditure) and as you can see it is reduced especially in cases of lower body fat.

These factors cause us to hold onto weight and make it harder to lose fat, especially the last little bit.

So when we finally finish the diet and eat normally again why is it that we can add fat on and easily pack on the pounds? It’s because your metabolism stays slowed down for some time making it easier to gain weight, because your body is using less energy. During this time your hormones are in a altered state which also predisposes you to weight gain. Going back to your regular diet can make you end up at the same weight as before and in some cases even heavier. The best thing to do after a diet is to reverse diet. Reverse dieting is slowly adding calories back into your diet. This gives time for your body to ramp your metabolism back up. Reverse dieting can prevent you from losing all the hard work you put in. Keep in mind while cutting to make sure to eat enough protein and lose weight at a moderate pace. Doing this will preserve as much LBM (lean body mass) as possible.

At the end of the day your body will fight you more and more as you lose fat. It’s a natural response to prevent the body from starving and completely losing all its energy stores. The biggest thing is focusing on a good diet, staying dedicated in the gym and keeping focus on your goal. Make sure after your diet not to overeat or binge, you don’t want to do all that work for nothing!