Checking your actual body-composition is a better assessment of health and can help better quantify your success. Body Composition helps answer these crucial questions:
- How much total body fat do you carry?
- Where is that fat stored?
- Is visceral fat decreasing?
- Is lean mass being preserved during fat loss?
- Is strength improving or declining?
- Is abdominal fat decreasing even if scale weight isn’t changing or is changing slowly?
- Are blood sugar, blood pressure, triglycerides, liver fat, and fitness improving?
You may lose only five pounds but gain strength, reduce waist circumference by two inches, lower visceral-fat estimates, improve fasting insulin, and preserve lean mass. That outcome is more meaningful than losing 15 pounds quickly through severe calorie restriction and in the process, losing a substantial amount of lean muscle!
The Scale Does Not Tell the Whole Story
The scale only reflects total body weight made up of muscle and other lean tissue, fat mass, bone, water, glycogen (the stored form of carbohydrate in muscle and liver), food and fluid in the GI tract and fluid throughout the body.
A rapid drop in scale weight is misleading. Early weight loss is loss of fluid and changes in glycogen reserves, especially if someone sharply reduces carbohydrates or calories. Over time, aggressive calorie deficits can also lead to loss of lean muscle and bone mass. This loss of muscle and bone is devasting to our health and independence as we get older, and in people over 40, much harder to build back after losing.
Muscle matters. Skeletal muscle helps regulate glucose, supports physical function, protects mobility, contributes to balance and fall prevention, and helps people remain independent with age. Muscle also gives the body a metabolically active place to store glucose after meals.
When people lose muscle during dieting, they may become lighter without becoming proportionally healthier. They may also experience reduced strength, lower exercise capacity, fatigue, and more difficulty maintaining weight loss over time.
The question should not be, “How much weight did I lose?”
The more useful questions are: “How much fat did I lose, how much muscle did I preserve, and did my metabolic health improve?”
Weight Loss at Any Cost Can Seriously Backfire & Jeopardize Health
Rapid weight loss in a medically supervised program can be appropriate in selected circumstances, especially when obesity contributes to type 2 diabetes, obstructive sleep apnea, fatty liver disease, severe mobility limitations, or cardiovascular risk. New medications and structured dietary interventions can provide meaningful benefits. But rapid weight loss must have a plan to protect muscle.
Very-low-calorie diets should not be confused with a balanced moderate calorie deficit specifically for weight loss. A balanced moderate caloric deficit is a meal plan with adequate protein, vegetables, fiber, essential fats, vitamins, minerals, and food volume to support staying with it AND preserve physical function and improve long term health, the goals that matter.
Very-low-calorie diets: severe calorie restriction affects more than body weight
A very-low-calorie diet generally provides fewer than 800 calories daily. These programs can produce fast weight loss and may be used for specific medical purposes under professional supervision. They are not a routine long-term strategy and can be difficult to sustain. They also increase the risk that weight loss will cause loss of lean muscle mass and bone mass if protein intake, nutrient adequacy, resistance training, and medical monitoring are insufficient.
Very-low-calorie diets can change body weight quickly, but the body does not interpret severe calorie restriction as a neutral event. When energy intake falls dramatically—especially below about 800 calories per day—the body adapts to protect essential functions.
Adaptations to severe calorie deficit include changes in thyroid hormones (altering ratio of T4 to T3, percentage of thyroid hormones in free vs bound state, etc.), resting metabolic rate, reproductive hormones, adrenal hormone production, bone turnover, mood, exercise recovery, and lean tissue preservation. These are some of the reasons that “faster” weight loss is not always better weight loss.
Research in very-low-calorie diet settings has found reductions in active thyroid hormone T3, increases in reverse T3 in some studies, and reductions in resting metabolic rate. In one small trial using a 400-calorie-per-day diet, T3 fell by as much as 66 percent while reverse T3 rose. Other studies similarly found declines in T3 and resting metabolic rate during severe calorie restriction.
This is sometimes called “sick euthyroid syndrome.” It means TSH remains normal, free T3 is low (a protective response to caloric starvation), free T4 may be low also. The thyroid gland IS still working properly to protect the body from damage in the setting of severe caloric (and energy) deficit. The protective response is to reduce liver and thyroid gland conversion of T4 to the more metabolically active hormone T3. The reduction in free T3 helps the body’s energy-conservation response. Lower T3, loss of lean mass, and reduced activity levels can all contribute to a lower daily energy expenditure during and after aggressive dieting.
The thyroid changes that occur with adaption to severe calorie deficit cause symptoms mistaken for “hypothyroidism” – fatigue, feeling cold, “foggy brain,” reduced exercise tolerance, sleep disruption, irritability, low mood, poor concentration, and oftentimes, a frustrating weight-loss plateau.
These symptoms should NOT lead to a self-diagnosis of hypothyroidism. They are a reason to evaluate whether the calorie deficit is too severe, whether protein and micronutrient intake are adequate, whether recovery is sufficient. A health care professional should assess the necessary steps to take to overcome the adverse effects of thyroid changes to very-low-calorie diets.
Insulin normally decreases when carbohydrate intake drops and calorie intake falls, which leads to improved insulin sensitivity as fat mass decreases. Clearly this is a desired goal for people with insulin resistance or type 2 diabetes. Keep in mind, however: The metabolic benefit of lower insulin does not eliminate the risks of prolonged severe calorie deficit that leads to under-fueling the body, inadequate protein intake or loss of lean muscle and bone.
BOTTOM LINE: fat loss should create a manageable energy deficit, not a chronic starvation signal.
- Special Considerations for Women. Very-low-calorie dieting can be problematic at any age, but the dominant risks differ across life stages.
- Premenopausal, reproductive age women: severe calorie restriction—especially when paired with strenuous exercise—suppresses the hypothalamic-pituitary-ovarian hormone axis. The medical term for this is hypothalamic hypogonadism, and it leads to suppression of menstrual periods, irregular periods, absent or scant menses, low energy, impaired ovulation, reduced fertility, and loss of optimal estradiol, progesterone, testosterone and DHEA production. A missed menstrual period is not evidence that a diet is “working.” If a person who previously menstruated regularly has no period for three months, develops persistent cycle irregularity, or has signs of restrictive eating or compulsive exercise, she should seek clinical evaluation and proper adjustments to the diet and exercise plan.
- The Female Athlete Trial: This clinical syndrome occurs in both younger and perimenopausal women due to loss of estradiol and testosterone (as described above) along with low vitamin D, and inadequate caloric intake for energy that causes loss of bone mass and increases the risk of bone stress injuries. This is where body-composition assessment, adequate protein, resistance exercise, balance training, and bone-health evaluation become especially important.
- Menopausal women: the immediate concern is to avoid very low calorie diets and overtraining that can cause loss of muscle and bone, leading to loss of strength and risks of falls and fractures. Estradiol has already declined and increased risks for osteopenia, osteoporosis, falls, frailty, and loss of independence due to hip and spine fractures. A severe calorie deficit accelerating these risks by causing lean-mass loss, lowering protein and micronutrient intake, and reducing mechanical loading on bone.
- A special note about Progesterone: During pregnancy, progesterone’s effect to decrease insulin sensitivity and increase fat storage is adaptive to serve the energy needs of the developing baby. In menopausal women taking estradiol, progesterone-induced reduction of insulin sensitivity (increased insulin resistance) has potentially negative effects when trying to lose excess body fat, which is already higher in menopausal women. So in patients I am treating, I use the least amount possible to achieve therapeutic goals, and adjust diet and exercise during progesterone phase of HRT to help reduce the increase in insulin resistance progesterone causes.
Menopausal women with a uterus who take estradiol DO need progesterone to prevent excess buildup of the endometrial lining and later malignant change with unopposed estrogen. Options are a daily low dose (100 mg) or cyclic short 12 days cycles at the higher 200 mg dose every 6-12 weeks (frequency depends on bleeding pattern).
Menopausal women taking estradiol who have had a hysterectomy do not need progesterone for menopause therapy. I have written extensively on this in my books, available the Truth for Health website. Profits from my book sales benefit the Foundation.
GLP-1 and related weight-loss medications
GLP-1 receptor agonists and newer incretin-based medications can be transformative for many people, but they have serious adverse effects you need to take into consideration. They do reduce hunger, support blood sugar control, and lead to meaningful weight loss in severe obesity and diabetes. In these patients, these drugs may reduce overall health risks and improve quality of life.
These medications do somewhat reduce visceral fat as total fat mass declines. That is a meaningful benefit. But the serious risk of the GLP-1 and related medicines is that they cause significant loss of lean muscle and also as part of the loss in lean mass, they cause loss of bone. They DO NOT exclusively cause just fat loss. You can minimize the loss of lean body mass by adequate protein intake, resistance training, and adequate balanced overall nutrition—but sadly most people taking these drugs are not given this guidance or do not put in the time and effort to follow it.
If you are taking a GLP-1–based medication for appropriate medical indications needs to ALSO pair the medicine with a muscle-preservation plan following these priorities:
- Include protein early in meals, when appetite is often best.
- Eat enough protein, even if appetite is reduced.
- Use nutrient-dense foods rather than relying on very small amounts of low-protein snack foods.
- Resistance train at least two to three times per week when medically appropriate.
- Continue regular walking, cycling, swimming, or other aerobic activity.
- Monitor strength, energy, exercise tolerance, waist circumference, and body composition—not only scale weight.
- Work with the prescribing physician if nausea, vomiting, severe constipation, or early fullness prevents adequate food and protein intake.
Medication can make fat loss more achievable. It cannot replace the nutrition and strength-training behaviors required to preserve muscle, bone and overall lean mass.
Dr. Vliet’s Recommended Supplements to Support Fat Loss |